Please take care with responses here. Anything that is obviously advertorial will be moderated, as well as things that seems like rants. That doesn't leave huge space for responses but hope the above makes sense.

Honest general questions though: does where you go for CLAT prep really matter hugely? Are some much more expensive than others? Are there any free materials online that could provide similar value, or in order to crack CLAT do you really have to pay for it?

Will try to guide the exactly what I feel,did and succeeded in it .In fact in my opinion clat coaching is not required at all. Now what you have to do . First read a lot good books ( fiction and non fiction) and improve vocabulary by few Norman Lewis books and Willey cat book ( made for comprehension and vocab, vocabulary.com ) .secondly use free pdf of gmat official guide and Manhattan guide for sharping critical reasoning .Thirdly use BSC Publication book for data interpretation. Fourthly for gk use dristi magazines ( for ias pre) ,byju magazine+search imp topics online, hindu and express explained . Fifthly use two test series ( [...] or claptrap or whatever you like as second choice) use their pdf freely available on telegram for legal reasoning and gk only .Improve logical and comprehension from test series only after mastering from gmat . If you are still not satisfied with your score then delve deep into the materials of comprehension and critical reasoning available in gmatclub.com ,again freely available. Remember, there are many benefits of self study, you use your brain more, less dependency on many average teachers (not all) .Give 3 hrs per day in class 11, 5 hrs during vacation, 3 to 5 hrs in class 12 .If you are a dropper, then give 6 to 7 hrs for first 6 months ,further increase it to 8 hrs . 50 mocks are must. Have a deeper look on past 2 years papers and sample papers provided by the consortium. Go through the minor details of syllabus. Final outcome will depend on many other qualities like perseverance, ability to focus,determination, wise use of media and of course speed of grasping materials.

Caution:
Did all of this. Improved my scores in Mocks too. In the end, I was getting 97-98%ile in RC and CR, and overall around 92-95%ile. However, I screwed up on D-day, particularly due to the shitty management. Honestly, they should hand it over to NTA. Mofo was blabbering throughout and sporadically was belling some weird alarm - time notice, Good Lord!

So OP your takeaway is: You can mess up even after doing all of this; Don't take a drop; Have a backup.

Hey. So, imo one should only join coaching if they have a problem with setting up a schedule and following it consistently. Otherwise, any coaching does very little except for helping you regurgitate the syllabus and prepare you for the stress test.

I never joined any coaching and prepared for CLAT along with my boards and managed to get into one of the Top 5 NLUs.

I'll provide you with the names of the coaching, and also give you some tips if you end up preparing on your own.

Firstly the coaching institutes:
1) CLAT Possible (Delhi and Lucknow)
2) Legal Edge (Bhopal only)
3) Career Launcher (Delhi)
4) Clat Prep (Jaipur)

Now if you plan to prepare all by yourself,
you can use the following books:

1) Logical Reasoning
RS Aggrawal: The f at book. But skip the 3rd part of the book with pictorials etc.
Do the first two parts. If you just want to practice verbal reasoning, you should buy the small white book of RS Aggrawal which just includes verbal reasoning bits.
NOTE: Don't use the syllogism techniques taught in RS Aggrawal, instead use the Venn Diagrams method.
This short tutorial was the best source I could find for mastering the Venn Diagrams during my prep:
https://youtube.com/playlist?list=PLhuF3CfgKa3bppaQ-sd5wF5tEFxEDdBgb

After you've done RS Aggrawal and some mock tests, switch to MK Pandey and complete it. Read it thoroughly and do every exercise. Prepare a separate register for each subject which would just include questions that you got wrong along with the answers.

After RS Aggrawal and MK Pandey, you should focus on speed and time management as well as Mocks and Online sources.
If you are adventurous and have time, you can also use Arun Sharma. It is a book for CAT but it really sets the bar high and would make you a Logic Wizard.

No more books required. The Mock Tests and Section Tests would do.

2) Maths
Take the important topics list from the Legal Edge YouTube video. (15 topics)

RS Aggrawal- Use it for the questions. Don't use the methods prescribed.

MK Tyra- Use it for the tricks.
A good YouTube channel that I used for preparing Quantitative Aptitude was Mahendra's Channel on YouTube
(https://youtube.com/c/MahendraGuruvideos). You can watch the videos on the topics which are mentioned in the Legal Edge video.

After all this, you should again repeat the mock test questions and the ones you got wrong. It is not about brute forcing, but actually learning about the number of question variations of each concept and topic.

Rest assured you'll do good if you know these variations.

3) English

DON'T use Wren and Martin. Unless you did school in a vernacular language or are genuinely weak in English, it helps very little in terms of preparation.
Buy SP Bakshi and/or HM Prasad. After doing these books and mock tests, go and solve Arun Sharma's RCs to humble yourself down and cry about low scores.

You don't necessarily have to read newspapers but if you have the time, go for it. You HAVE to read Norman Lewis. You can do quizzes on Vocabulary.com
There is a vocabulary app by Magoosh on the Playstore. That is a good resource too.

4) Legal Reasoning
AP Bhardwaj (With a pinch of salt). A BIG NO to the Universal Book unless you want to be confused.
Mock test questions and section-wise questions would be crucial.
Also, Legal Reasoning from Harsh Gagrani's book (The big fat guide).

5) GK
Make a register with important events.
GK Today news+ Quizzes, Cloud Affairs, LegalLE magazine, Darpan, Testbook App Quizzes etc.
Try to get hands on Compendiums from Telegram and read them.
Make a register for the questions you got wrong. This saved my ass as I got +3 marks in GK directly because of revising this register on the day of CLAT.

Mock tests and timing are key. Although it was much worse during my time when there were 200 questions. Try and do hard RCs and basically get comfortable with the language as it can make or break your final result.

Mock tests
1) Legal Edge
2) Clat Possible
3) Career Launcher ( Has the biggest pool of students so its a good indicator of preparations).
4) Clatapult ( Not many know about this one, but its a coaching provided by NUJS students and alumni. Their mocks are very well curated).

Personally, I chose Clatapult and Clat Possible but feel free to pick your own. Also be on the lookout for free All India Mock Tests that these coaching centres provide.
I was also able to buy a lot of books because I spent zilch on coaching institutes and instead used YouTube and Khan Academy to learn about any concept that I had a problem with.

Best of luck. Hope you bell the CLAT!

Coaching institutions are a scam. The requisite list of books required is readily available online. Instead of sitting in classes, just buy the mocks from all CL, CP and LE. You can also get CL’s study material. And you’ll still save a ton of money. Also give CLAT for practice even if you’re not eligible to get into a uni. If you are in 11th class, just get up and appear for clat regardless of the fact that you’re unprepared and are not eligible for admission in a university. You will get a taste of how a real time exam actually feels like. Some of the brightest students I knew who toppers in mocks underperformed in clat because they were not ready for the actual exams.