So it only took 11 days, but the lasers are finally here. Was talking with TheDude about how I'm going to power them, and he suggested a USB hack and pointed me towards this maximumpc article that covers the basics. Have already checked them out to make sure that the light is visible on the webcam I'm thinking about snagging by simply hooking them up to the cellphone battery for a test run.
The numbers: I got 4 lasers, 3.2V each, 25 mA, currently unknown resistance. The plan is to appropriate the USB cable from a dead MS Intelliexplorer mouse and use that for USB power source. The USB port runs 5 volts at 100 mA in lower power mode, so I shouldn't need to worry about asking it for more power or anything.
The shopping info: I ordered 740 nm lasers with 89 degree line splitters from aizix.com for $11 each ($8 for laser, $3 for splitter attachements). Not entirely sure I would recommend them, but as of right now I don't know of anyone else who isn't selling just the diodes or the laser already as part of some other device.
1) obtain the acrylic sheet and figure out how I'm going to mount these suckers (estimating $20 for the sheet)
2) acquire a camera (thinking about a $20 gigaware cam from The Shack) and modify it to remove the IR filter and possibly in a regular light filter by butchering a floppy disk
3) splice work for the lasers and make sure that the camera can see the touches
4) clean install of linux on an old PC and see if I can't get the nuigroup software up and running
Projector and the frame to hold all this remains question marks for the time being.