http://www.utilityfree.com/hydro/
^Scroll down to the bottom of the page for the generators and prices.

And >
http://www.absak.com/catalog/index.php/cPath/33_89
ABS Alaskan also has a library >
http://www.absak.com/library/hydro-power
^Click the links on the right for the articles.

I recently had some work done on our pump (and learned it pumps 300 gallons per minute!) and asked the guy about water turbines. He told me our town uses one during the summer but they take it out in the fall because the creek (really a river) would tear it up with its turbulence. I know that's not very helpful as I haven't any idea what kind they have but it's a factor I hadn't considered.