Looking for simple, inexpensive, handheld wireless controller

I'm interested in doing some classroom-based research using student participation via hand-held response systems (like the so-called "clickers"). The downside of clickers is that they usually only have a numeric keypad and a couple function buttons, which are handy, but limited for the interaction I want to have available.

I'd ideally like something similar to TouchOSC on the iPhone, but instead of mainly having slider-based controls, I'd like four screens: numeric keypad, a regular keyboard, a screen with several sliders and some buttons, and an XY control with several buttons. If need be, the slider screen could be incorporated into the numeric keypad screen, but at least one slider is essential for "real-time" assesment (instead of keying in a rating every X minutes, the student could hold a finger and continuously send values). The XY is needed for mouse-like interaction, or sending pairs of parameters for a geometry or music app, for example.

I'd like to have this be touch-screen (only needs single-touch and doesn't need pressure-sensitivity), but I realize that this implies a decent amount of underlying coding to make the graphics at all, and I would probably want to avoid that unless there's an open-source platform I could use. Otherwise I could do it with regular hardware buttons and dials, but that's kind of clunky.

Essentially, I want something similar to what you find in TouchOSC, but with the additional features mentioned, without having it actually be an iPhone (even if I could get old iPhones cheap). I want a new or generic device that ONLY does these things, rather than the many things the iPhone does, for reasons of cost and of not having distractions.

It would communicate using OSC or whatever's easiest, over the wireless network, to the teacher station that's running a receive Max patch. This way, students could be rating things, voting on answers, or interacting with various patches from their desks or anywhere in the room, and the results could be seen (or not) by everyone, via the projector. Basically, I want to target the "middle ground" between a projector-fitted classroom that has a laptop for everyone (great for some things but expensive and distracting) versus having only a projector. This setup would allow substantial interaction without much cost, and students could simply use provided devices without having to purchase them.

If anyone has ideas about ready-made devices that would do this (or could be modified), that would be great, or info about a DIY version, as building one is also a possibility. Essentially I'm looking for thoughts and advice on where to do more research.

Thanks wizards!