I agree that the price is very good; it is so good that I have to wonder why. Since Colt has messed with the marketing so much, the Commander term no longer suffices to distinguish alloy-framed pistols from steel-framed ones.
If it has an alloy frame, look for cracks, especially around the slide stop area. I would also check to be sure that the barrel sits about 1/32" forward of the frame. If someone has used a Dremel on the frame feed ramp, it would be a very expensive fix. If it really is in good condition, grab it. That price is a few hundred lower than I see marked on some 9x19 Commanders in horrible condition. I paid only a few hundred less for a complete pre-Series '80 9x19 Commander upper a year ago.
As mentioned by BluesBear, most 1911 parts will fit; the exceptions are the barrel (duh!), barrel bushing depending on which barrel Colt used, extractor (there are specific 9x19 extractors), magazines, and recoil springs (I like 13# or 14# recoil springs in 9x19 Commanders). Magazines can often be a big issue with reliability in the 9x19 1911's, especially on feeding the first round from slide lock and locking the slide back after the last round has been fired. I have had very good luck with the Metalform "Springfield Ramp" magazines. Grips, grip safeties, and mainspring housings are all common with any other 1911 not using a firing pin safety.