It is a range, depending on features from the ASUS RT-N56U (N dual band) up to the RT-AC68U (AC1900), excellent best in class for each but not inexpensive. I get to play with them a lot when I test them before a client install, and they are certainly my favorites, but they do take a bite from the budget.
Also, at this point there is only *one* 3x3 AC1900 wireless AC adapter, and ASUS but it is $100 just for the PCIe adapter. Every other adapter out so far is AC1200 at best, IMO 802.11ac is just not ready for prime time unless you just want a great wireless bridge.