Hey Annie, sounds like a fun project. If you're near any of these
Northern Tool locations, you could get a catalog. They have about 6 pages devoted to ponds, pumps, etc. It may be something you could use.
My wife feeds the humming birds out at our place in Wy and I provide water to them and our motor home with a ram pump I made out of pvc pipe and fittings. It was a fun project and it pumps about 450 gallons a day out of our spring. The pump looks something like this commercial pump.
So if you happen to have a spring and a downward slope of about 3 feet, you could power the water feature for free.