Yeah, I'm pretty much in the same boat. I have a Netgear wireless router, and I'm looking for a bridge to go with it. I saw one online at CompUSA for $99 and one instore for $129. I don't think BB even carries bridges or game adapters. Circuit City might have one. Let me know what happens with your search.
Note: It's an ethernet bridge (which is essentially what your gaming adapter is) and you may need a crossover cable as the one I ordered only came with a straight through)
One of the most ignored features of many wireless routers is that they support a bridge mode. If you've ever wondered why wireless bridges are so pricey you were correct to be suspicious. Any router can perfrom the same task if the internal software has the mode. It's actually a much simpler task than its normal duties.
Many wireless routers are only compatible with the same brand in bridge mode but they've become so inexpensive you can often buy two for much less than you'd pay for a dedicated bridge.