Building an Open Source "Clicker"?

fieldtest asks: "Most Slashdot readers have read about "clickers", remote control style devices that students use to wirelessly answer a teacher's questions. Unfortunately, as a college student, I have had less than stellar experiences with these clickers. I hear complaints from my professors and fellow students often as well. So, I want to build an open source clicker system for all universities to use. I believe that this is a prime opportunity to show how powerful free software can be. So, what do the talented people of Slashdot recommend?" "The problem is this: a clicker system requires...clickers. What I need are remote controls that have a minimum of 6 buttons (for users to select options with). The sticking point comes when a button is pressed -- the remote must send the option choice, as well as a unique ID specific to the remote, so the clicker software can distinguish between different students.

I've experimented and Googled around. I've tried standard TV remote controls combined with an USB-UIRT receiver, but the range was too low. Googling shows some interesting programmable remotes, but they're far too expensive ($100+) to have each user purchase one.

How should I go about building the perfect clicker and receiver system? Any suggestion is welcome, from IR to radio, from Bluetooth to ZigBee based communications. Recommend a commercial product, or a do it yourself solution. Please also recommend a receiver device, and a way to connect it to a computer. Also, if you recommend that I just build a custom circuit board for the remote control, please give some references and examples of how it should be implemented."