Atmel's "at90usbkey" development board for their AVR+USB chip family costs $33 at Digi-Key.  Right now they've got 105 in stock.  It programs right through its USB port using Atmel's free FLIP 3

About a year ago I started to use their accompanying demo software to make a USB chordite but gave it up because they didn't have their source converted over to the free WinAVR (i.e., avr-gcc on Windows) compiler.  It was just too much hassle to convert it myself.  

But now they've done that for me. They've now got a mouse demo   that compiles on WinAVR and runs on the at90usbkey board, which has the at90usb1287 chip.  They've also got a keyboard demo   that runs on the not-so-cheap STK526 board ($211, two available) which has the smaller, cheaper at90usb162 chip which is really more suitable than the '1287 for keyboards.

So now the project looks as follows.

(1) Combine the 2 demos to make a mouse+keyboard demo that runs on the 'key board. This is a USB compound device with 2 interfaces.
(2) Replace Atmel's keyboard part (which merely prints a canned message when you punch the joystick button) with Chordite keyboard code.
(3) Replace the mouse demo part with the mouse Chordite part.
(4) Move the code back to the '162 chip and lay out a little board for it.
(5) Use emachineshop for the physical design

Voila, USB Chordite (or, for that matter, other chording keyboards) for the masses.

At the moment I've finished steps 1 and 2 and I'm starting on 3, which should be the easiest.  I know what I want for 4 and 5.  The beauty of all this is that Atmel has made it unnecessary to learn much about their USB implementation or even USB in general.  They just give you a nice little niche to plug your stuff into.

Unfortunately the way I understand Atmel's license I can't publish the source code that results. I can only post a hex (i.e., executable) file.  The 0.1 version should be in the files section within a week or so.