How much you pay for an AICS depends on what you want. There are 3 types, (1,1.5,& 2). stage 1 is a "plain" stock, stage 1.5 is a fixed stock with an adjustable cheek piece. Stage 2 has an adjustable cheek piece and a folding stock.
I see you've started another thread about the prices, so I won't get too far into it. You can get the stock for less than $1000, and the more accessories you add (mags @$100each, PH bipod @200, etc) the more you end up paying.
Cheers.
Tim