I personally pay 50 reais a month for training, and I know it's pretty much the exception and I consider it an insane deal, both for the amount of classes and the price. There's definitely not a school in every corner, at least not in where I live.
I understand that some schools can really be expensive, both regarding money and regarding the amount of classes you get from it, but it really depends on the area. From what I can tell, jiu jitsu is always more expensive than other martial arts on the same area, although definitely not as large as the difference between BJJ and Judo on your area.
Labeling jiu jitsu a sport for "rich kids" is wrong, in the sense that sports as a whole are something that most of the population just don't have access. They aren't taught in schools, they aren't practiced in any way that could actually lead you somewhere, and unless the local government has some kind of sport program, get ready to shell out cash for any kind of training. It's just like it is.
Also, a good way to explain a good part of why jiu jitsu is expensive is that, while some guys are making a living out of it, tournament holders and associations are definitely making a profit out of it, and a huge one.