Let's try to narrow your search a little first. What range of flow rate do you anticipate? How precise and fast does this measurement have to be? Will this be measuring water flow in piping, a canal like aqueduct, over an opened flood gate or some other conveyance? After answering these questions, you might try this link to search for some products http://www.globalspec.com/

My application is going through a 1" pipe. I did some more digging around and found the following:

http://catalog.gpi.net/viewitems/economy-electronic-digital-meters/tm-series-water-meter?&forward=1

Anyone have any experience with these meters or this company?

Oops I forgot to link it!

http://catalog.gpi.net/viewitems/economy-electronic-digital-meters/tm-series-water-meter?&forward=1

have you ever considered to use ultrasonic flowmeter ? if there is not big particles in the water ,you can have a try to use it . testing pipes should be full of water when working .there are economical types . I have bought one from this company .

good luck !