but what If I don't want to post
honestly... I couldn't tell you how much it's going to cost... the current gen adapters are definitely no where near the $30 price range.... MSRP is $109 http://www.xbox.com/en-US/hardware/xboxwirelessadapter.htm
The cheapest 3rd party one (generic wireless bridge because that's what it really is) I've ever seen was about $75
It's hard to say how much they'll charge for the adapter in the next gen console. I'd be willing to bet it will be a lot cheaper. I say this because the current gen adapters are essentially a wireless bridge, where they convert ANY standard wired connection in to a wireless connection. The Next gen on the other hand connects via USB and acts more like a typical Wireless USB adapter. Generic 3rd party brands of those for PC are as low as $15 or $20 but are typically in the $50 to $60 range. The reason is a lot more of the work is done with software and they get power from the USB port instead of from a wall wart (which does save quite a bit on the cost). I would imagine that the 360's adapter will be a bit more than the generic 3rd party adapters you can get now because unlike the current gen generic adapters wont work without drivers... and the only people who can put drivers (officially) on your Xbox is MS. So they'll probably jack the price a little. Also the fact that it supports A, B and G standards.
So I would imagine it will be considerably less than the current gen adapter but quite a bit more than the low end 3rd party USB adapters.
If I had to make an educated guess... I'd say it will be about $60 give or take.