What nutter said.
Pre-ban M1A's are in demand because they were made much better, not because you could hang all sorts of stupid shit off of them in ban states. It's a seller's market on any M-14 clone.
Post ban M1A's should be a little lower, but this is a somewhat captive market, I'd say $900-$1100 for a lightly used version of any of the more basic guns, up to $1800 for the national match with the krieger barrels, Nm sights and triggers. The scout squad and so com maybe $ about what you are paying. I always felt that the spring fields are hideously overpriced but they sell, so there you are.
There are also the Chinese polytechnic clones. These go for $800-950. They ARE all Preban. And often as good, if not better than the springers. Sometimes the Chinese would fuck up heat treating some parts, but there are plenty of spares on the market that I wouldn't sweat it.
Lastly, Frankfort arsenal makes some serious M-14 clones. Really nice, and the price reflects it, but not really that much $$$ compared to the higher end spring fields. They are not something you find in a gun shop typically. Much like a unicorn, sometimes they just show up. Meets to order direct from them.
Personally, I like the traditional stock and look the best. I would personally go with a polytech or older springer for the lower end, and Frankfort if I was looking for a martch gun. You guys that like to to dress them up like transformers or mechanical insects would probably be after the so com or scout squad whatever. I think Sardo has the crazy looking sage stock. And Dempsey has the so com.
Neat guns.