Depends on the condition, and how complete it is--are those just the bare boards? If it has the art, then I'd say that it's a very good price.
The Garegga board is pretty hard to find, and those that are selling it want a silly amount of money for it, but on the other hand, you could just get the Saturn disc cheaper. My interest in arcade boards is over with. Unless you're good with fixing/maintaining them, it's just a pain in the ass to collect, not to mention a money sink compared to console versions.
Just the boards. I just got an astro city arcade machine and I want to play some shmups on it but abit of me don't want to pay that much for donpachi and battle garrega since I do have them for my Saturn. I might go ahead and get progear since I always wanted to play it and I don't have to put the screen vertically.