So you think that the instructors in San Diego could be forming a cartel? Where they basically agree on what price they should charge, and they don't compete with each other? I doubt that's the case, and it would even be illegal if they were agreeing on prices as competitors.
No I do not think they are intentionally price fixing, they see what others pay and have full schools so they do the same. No way that ALL of those schools have the same bills or expenses yet even the school with the LEAST bills charges the same amount as the school with the MOST bills.
I just think that the demand for BJJ is relatively inelastic. Many people decide where to eat based on the price, but I don't think that many people decide where to train based on the price. If BJJ instructors thought they could get more students by lowering the price, they would, and they would advertise their prices openly on their websites instead of making you come to an intro class first. Also nearly all of them offer some kind of discount if you pay a few months in advance, or sign a contract, or make some other kind of commitment. They don't just want to get people in the door, they want to sign up long-term students. The guys that just want to find the cheapest place to train probably aren't going to be the loyal students that keep coming back several times a week for many years. Those guys come because of the quality of the instruction, and the facility quality and location are big factors too.
Personally, I think that the price of BJJ training is just about the last thing I consider when choosing an academy, just as long as it is within my budget. Like, if it's $75 vs. $125, I really don't care about the price difference and will probably even pick the more expensive one because they are going to be open more days per week, have a better facility, have a more highly qualified instructor, or offer bonus classes like no-gi or kickboxing, whatever. If it gets up around $200 though I will probably decide that this is out of my budget and look for a cheaper option.
Again that would depend on the instruction.
The other point I could make is, how much does a health club membership cost? A good one probably costs close to what I would pay for BJJ. A 24-Hour Fitness is maybe $50/month but I probably want to get personal training along with that. A fully-equipped Crossfit gym in my area costs $175/month for unlimited! I need to work out anyway, so if I'm not spending that money doing BJJ I'm going to spend it doing some other type of exercise. That's why my demand is relatively price-inelastic as long as it's within the maximum amount that I feel I can afford to pay.