what kind of volume are you going for?
if you need a lot and can get back pressure to close them then the irrigation valves will be your best bet as you can get them for around $20 and they come in lots of sizes
if you don't need as much flow you could get a ice maker valve unit but some of them have 120v coils so make sure you get the right one
if you need something for low or no pressure water you may want to make something using a check valve and a servo motor or solenoid to open the flapper (just install the check valve backwards and drill a hole in the top plug to run your wire threw that will attach to the solenoid or servo) or you could do the same thing with a toilet tank flapper valve