Another great place to buy a regulator is your local propane dealer.
(I'm talking about the one who sell and deliver propane in bulk to houses and such) In my area there are several, Amerigas, Titan propane, Simmons propane..ect.
Two years back I went to Amerigas with a sketch of what i wanted to do. Thier tech set me up with a regulator, gauge, hoses, and quickconnet fittings for around $60.00-$70.00
Another option is to try calling on your natural gas company, my gas company does carries some items for propane