Very nice work.
I'm looking at these:
http://www.ebay.com/itm/New-Solenoid-Valve-Air-Water-Liquid-12V-DC-1-4-w-Push-connect-fitting-NC-NPT-/121242551851?pt=LH_DefaultDomain_0&hash=item1c3a9e862b
Quite a bit cheaper. They react slightly slower, only require 400 mA (vs 600 mA), and are less...