You can get Asus N300 adapter for 900 bucks. Its a good one.
I am using Digisol 300N adapter since the last 6 months and its working great. The best part is its got a Lifetime Warranty. It also costs 900 bucks.
My cousin is using a D-Link 300N adapter. This one also works fine. It also costs 900 bucks. Comes with 1yr warranty + 2yr after online registration.