Build your own... (Score 1)

I had the same problem a while ago. Most of the ones availible are cheap POS. If you have the time and expertise, or can find someone that does, you can build your own from a PIC microcontroller. Microchip even gives the software away, and the schematic. (One note about the schematic is that is has the clock and data pins to the PS/2 port backwards.)

Microchip's Application Note

Microchip even provides gives out samples for free, you just need to find someway to program it.