http://www.agrisupply.com/product.asp?pn=64494&sid=&eid=
$29.95 shipped. If you go low pressure you will have to drill out the jet.
They also have http://www.agrisupply.com/product.asp?pn=40282&sid=&eid= for $9.99
Watched it for the first time last night. Loved and set it up to record all new episodes. Its fun to see the scale differences between 5 gallon batches and their setup!
Most people recommend the Honeywell VR8200A2132.
Pexsupply has the thermo couplers, and pilot burners that go with that valve.
PID Temperature controllers seem popular. http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=3
Metal is going to be the easiest to work...