I've been collecting my PSP games for a year or so, because I've bought my PSP only between the end of 2010 and the beginning of 2011 (I can't tell the exact date).
Here, in most of the stores, it is pretty difficult to find games apart from the same 10 "hits", like PES, GTA, God of War, etc. However, as the gaming distribution is ridiculous here in Brazil, and the market is huge (20m living only in São Paulo and nearby cities), there are some stores specialized in games that import a great variety of titles and sell them to the "hardcore" gamer. And I, as a rabid fan of JRPGs, must resort to those stores.
Curiously, these games are much cheaper than what you find in the big retail stores. The big retail stores sell PSP games ranging from US$65 to US$130, while in those specialized stores it hardly hits US$65 (games are naturally expensive here because only recently the government took it out of the gambling category, which meant very high taxes for games).