I bought mine on eBay for $202 - you CAN find reasonably priced machines, especially if you're willing to take one that is less than perfect looking. Mine is in excellent shape functionally but has some pretty good wear on the decals. I bought mine to use rather than to display so I'm extremely happy with it. I got a case in good shape with it, a manual, and a box of 20 bobbins too.
There's always an element of chance when buying online - I had no way to verify if the motor was in good shape, etc. but for $202 I risked it and got lucky - she sews like a dream and shows evidence of plenty of love and maintenance during her life, along with plenty of use.
Locally, I can almost always find a couple Featherweights at the larger antique malls. They're usually in really good cosmetic condition and have price tags around $380-425 and come with a nice case and a lot of accessories. They don't seem to sell, though - the same machines will be there for months on end.
There are a few people who restore and resell FW's at quilt shows and expos. There's one who comes to our local quilt show and he sells restored FW's as well as repainted ones. His restored classic machines usually have stickers in the high $300's (and up, for rare versions) and a repainted machine...I want to say he asks high 500's for those but not positive. I have no idea how quickly he sells them.