Your best bet would be bluetooth. Normal wireless requires RF and usually pretty close. Mostly depends on where you plan on "hiding" your desktop.
Bluetooth can go out to 33'. YMMV. My bluetooth headset doesn't like walls much so penetrating a wall can be difficult.
I like the idea of attaching to your TV. I am building a portable gaming / work rig here shortly (described in a thread from a few days ago). When on the road, it'll be attached to a Dell 24" LCD monitor and when at home hopefully attached to a 62"
For gaming, wireless is bad. Latency can get ya killed so I am going with a completely wired solution. My situation is different than yours though.
Check
www.newegg.com for wireless mice & keyboards. They have a pretty decent selection and are usually cheaper than other websites. You may also want to check
www.buy.com and
www.bestbuy.com as they have occassional sales that make it cheaper.
Good luck