$100 for a wireless adapter? MS must be joking! That's highway robbery!
I must have read that at least a thousand times in the past week, and every word of it is true. The official 360 wireless adapter is simply way overpriced.
But what alternative do we have?
How about a wireless to ethernet bridge that only costs $40 or less? Netgear, Linksys, Hawkings, and many other companies make simple bridges that receive wireless, and convert to Ethernet, which would bypass the 360's security on peripherals. As far as the 360 would know, it would be on a wired network.
So, buy the MS wireless adapter for $100, or go with a 3rd party bridge for $35-$40.
Tough choice, eh?