What is the best way to connect a mouse and keyboard to an XBox 360?

My roommate loves playing First Person Shooters on the 360. I do not. Usually we’d game on the PC, but he has some medical problems that can make it painful to use a mouse for too long. I’m willing to deal with the splitscreen aspect just fine, but I feel like I’m trying to maneuver the Mars Rover when I play these games with a gamepad.

I’ve seen the 60-odd dollar hookup they sell online, but I was wondering if anyone knew a cheaper way to plug in a mouse and keyboard so I can use the WASD set up for first person shooters.