bennelson -
I have seen that model on web sites in the past. You should be able to make that version for $20 to $30 in parts. Here are you-tubes of a custom version that uses the same container :
01 - Hydrogen Booster Test
02 - Hydrogen Booster Test - The BIG Bang
I have one (
http://www.hydrogen-boost.com/), but I haven't been willing to do all the other stuff needed to make it work properly, so it's on the backburner.
This dude is doing lots of stuff right now :
HHO Generator
http://flapdoodledinghy.com/HHO_generator.html
Tons of detail on what he is figuring out.
CarloSW2