Wall Mart reflector $6 , and use something heavy to clamp it to while on the desktop - a brick works well, I use an old microphone stand. (mic-stand also about $8 from Radio Shack)

Look for light reflectors that are white or silver (avoid colored reflectors!)

Wall-Mart, Target, Big Lots, K-Mart ... etc. etc.

Buy table top tripods with reflectors on E-Bay. (Watch out for shipping cost!)

The key to all of these is to get the correct 5000°K fluorescent bulbs. I prefer the spiral bulbs (sometimes called "trumpet" bulbs - spiral changes size) as they put out more light in a forward direction.