If you can get the serial, call Springfield and ask them what kind of rifle it was.
I picked up an 88 vintage M1A for 1300 a couple years ago. Bedded stock, which I thought was weird, and NM sights. I was wondering wtf did the previous owner do to it. I called Springfield to verify that it was a preban...
..and it turned out to be a SuperMatch M1A.
Talk about a steal...the guy I bought it from had no idea what he had.
Run the serial. You might be getting a better deal than you think.
For me, $1500 for a minty Springfield M1A, pre-ban, isn't a horrible deal. You can probably do better (how many mags does it come with?)...but in a couple months, the market might swing the other way, and you might find 2k to be the going rate.
I'd say jump on it, and eat any possible bad pricing, and hang on to it. 20 years from now, you'll think you got an incredible deal on it, either way. I know I will, on mine