If you look on ebay like the user above mentioned, it's dirt cheap right now for the camera and 50mm lens. I would say 50 bucks. I saw one auction today that had the lens, the camera and a flash for cheap.
I have an AE1, and it's a great camera. Although, my Dad paid a lot for it for afew years ago
Search for the equipment on Ebay, and then check out the "completed" listings. This way you can see auctions that ended and what the cameras are/aren't going for. Also check out these companies; they are both very reputable used camera dealers. They will be more expensive than Ebay, but their return policy may be better than Joe Blow Ebay.