numrich has these parts available

Numrich Gun Parts Corp. - The World's Largest Supplier of Firearms Parts and Accessories

The only thing I can say is use your best judgement. As you say, prices are all over the place and if you're not in a hurry your patience will be rewarded. I waited until i found one for $400. The going price at the time for one in that condition was $500-600. These pistols are old enough that they should be checked by a competent gunsmith before firing anyway.
If you're looking for a shooter, then don't worry so much about visual condition; you can refinish it if you want. There's not much that can go wrong with one of these, and parts can still be found. Magazines are pricey if you can find them.

+1 on Numrich - if they don't have it, you don't need it! I've wanted one for years, but never seemed to find one. Good luck!