Which Android phone with ICS should I buy in Range of $400 ?
In general though, the HTC One X (gdgt.com/htc/one/x/), One S (gdgt.com/htc/one/s/), and One V (gdgt.com/htc/one/v/) are the newest phones to come out with Ice Cream Sandwich, and the One S and One V are probably within your price range if you're looking for a carrier subsidized phone.
There are not many phones with Ice Cream Sandwich are out right now, and most of them are new. This means that they are generally over $400 if you are looking for an unlocked phone.
If that $400 is on contract, then you will have more options