Been several threads on them lately. Personally I have one and flat love it. Almost no recoil, and accurate beyond belief. I also like the 20 round mags that are standard, with a 30 available. Don't let people tell you ammo is expensive. It does go on sale every now and then and compares pricewise to many of the brass cased .223.
Haven't priced one lately, but I would check Gunbroker to see what they are selling for. Look for sold auctions to get an idea.
Locally I would check Bradis, Plainfield, or any of the other locals. Online Buds would be a good choice.
I was in a BigR today and they had the ss197 ammo for $21.97...not bad price as I have seen it for as high as 28 or 29 bucks.Also harder to find than others...wish Wallyworld had it!