If you're willing to take a risk on eBay, you may be surprised at what you can get.
About 2 weeks ago I picked up a 17 inch DLSD/HR, 2GB (A1139) for $50 or so, as 'for parts / untested' as it didn't come with a PSU.
When I got it, aside from a missing Command key and missing feet, it works perfectly. No imperfections on the screen and pretty minor wear on the case.
I replaced the HDD with a PATA->mSATA adapter and SSD I had laying around, bought some feet and a new key, unbent an imperfection near the DVI port and now it's a pretty awesome machine.
As far as I can tell everything works fine, keyboard backlight, SuperDrive, all ports, LCD, etc.
Of course, it could have been a piece of junk, useful as nothing but a paper-weight but it turned out to be one of the best eBay purchases I've made.
Pro-tip... If you take it apart, don't accidentally try and screw one of the case screws in the DVI holes... That is somewhat challenging to remove.
I'll post a pic in the Club 17 thread