[sanswork]

Look for model jet engines they get to be surprisingly big. I haven't looked them up in a number of years but I wanted to build a jet powered bike in a previous life and if I remember right the only thing stopping me was price. Also runtime sucked for them all.

[Robotbeat]

For between about $2500 and $4500 (depending on thrust), you can get a small model jet engine: http://www.chiefaircraft.com/radio-control/turbine-engines/j...

I love these things. I love enabling gadgets that enable hobbyists and garage entrepreneurs to do crazy things like this that would normally require a military program to fund.