I got mine off of eBay. I got mine fairly cheap. Think about $20 each. Mine are rated at 15psi, but I only run at 1/2-1psi.
Be sure to reference the ASCO site to see if they are Normally Closed valves, max pressure is within range of your propane/NG pressure.
Are you using 110v, or 24v, 12v etc...