I looked over the prices and some seem reasonable. They range from under twenty dollars (US) to more than several hundred depending on the size, output etc. Somewhere they suggest using these in place of a solar PV panel.
http://www.tegpower.com (http://www.tegpower.com)
I've not played with this. Seems logical.
I have heard of folks experimenting with alternative solar power by cutting the tops of 2N3055 transistors, and exposing them to light to produce electricity.
.99
Crazy! I swear that is Dr. Stiffler in those TEG videos which reminds me of a guy whom had one looped up with an SEC and some hydrogen candles. I didn't look too closely at it but, it appeared to be self running. Once the SEC had enough juice to get the hydrogen candles burning, it seemed to self run. Kinda interesting I guess though, I don't know if you can get much more out of it to do any real useful work.