I'm only finding pricey electrically-powered valves ($20-$35 each) that assume you have a timer and wiring to control them. That kind of timer can cost $100!
(
http://www.dripworks.com/categ...)
Based on no experience except browsing catalogs, it seems less costly to skip the valves and dedicate one cheaper timer to the whole misting bench. Use manual on-off valves if you need to enable or disable zones occasionally.
Then you can use a $40 battery timer with just cyclic "frequency" and "duration". HD might be cheaper than online, for a battery-powered timer. But this plus a $30 valve might serve a one-zone misting bench.
http://www.dripworks.com/produ...
http://www.dripworks.com/produ...
Or here's a $30 timer that boasts about setting ON times to the exact # of seconds. I'm not sure about the wiring, but it looks designed to plug into a wall socket and have just one AC output ... bu the ad talks a bout a built-in rechargeable battery (???)
http://www.mistking.com/Digita...
Have you seen these? ... Never mind, I see they cost $250!
"The Mist-a-Matic System utilizes a stainless steel screen to simulate a leaf. The screen is located
on the propagation bed where it receives the same amount of mist as the plants. The screen is
attached to a switch that activates the solenoid valve when it drys and shuts off the valve when it
has collected enough moisture."
http://horticulture.oregonstat...
http://growerssolution.com/PRO...
