To answer your original question...

All (or nearly all) irrigation valves are 24 volt ac. Nearly all are normally closed (power to open).

For the old school brands (Champion, Rain Jet, etc...) you can buy 120 volt replacement solenoids, so you can run it directly from a electrical outlet (USA, at least, don't forget the GFCI). These valves, and the replacement solenoid, are pricy. Expect to pay $150 ish, way more than a 24v valve and transformer.

Pretty much any solenoid valve and transformer from the irrigation section of Home Despot or Lowe's will do what you want.