I don't know what your budget is, these cameras can get pretty expensive. When you said high speed this is the first thing that came into mind.
I don't really know about any cheaper ones. There are online places that rent them out.
Another options is to use the twixtor plugin with after effects. This can achieve a really nice slow effect but can at ties cause some distortion at times.
If you don't want to buy the twixtor plugin you can use the time remapping plugin that comes with after effects. It is more of a pain I think though. I only use A.E., so I don't know what other programs have to offer.
Here is twixtor in action:
|