My brother got this.

16€ — "The USB Overdrive is a device driver for Mac OS X that handles any USB mouse / trackball / joystick / gamepad / media keyboard and any Bluetooth mouse from any manufacturer and lets you configure them either globally or on a per-application, per-device basis."

Amazon: http://www.amazon.com/Logitech-Cordless-Laser-Notebooks-Silver/dp/B001FDRW5W

Review: http://www.ocia.net/reviews/dinovonotebooks/page5.shtml
Amazon: http://www.amazon.com/Logitech-diNovo-Keyboard-for-Notebooks/dp/B001FB55GC

$150

$50

$300-325. "The Advantage USB contoured keyboard sets a new standard for ergonomic keyboards. The Advantage line incorporates the same advanced ergonomic design as our other contoured keyboards and delivers additional features not found on other USB keyboards."