Surplus turbines and turbojets are plentiful and relatively inexpensive. I've been looking at them quite a bit lately for a homebuilt project I've been doodling with (full scale Fieseler Fi-103, German WWII) and it's very entertaining to see what others are doing with them. There's also a big community building and improving pulse-jets as well, which is extremely entertaining if you know anything about pulse-jets!
Here's a link to a fellow's site that has been doing some fun pulse-jet tinkering: http://www.aardvark.co.nz/pjet/
And a couple pics of his Lockwood-Hiller valveless powered dragster: