Home Depot, Lowe's, or any plumbing supply store. call em first and tell em what you need.
Also try calling Bulkhead O' Rama! can't beat their prices anywhere.....guaranteed.
John
Try www.grainger.com. They are a large industrial supplier and they have TONS of sutff. Their website may be a little hard for you to navigate so if you need some help e-mail me at Scotts@valex.com.
Scott
I actually got lucky... my lfs carries them.... but there also not like ***** or any other lfs.. This guy knows what he's doing and has actually lost sales w/ me becuase he has helped me out and told me i don't need certain things... If you have a good lfs they usually carry plumbing supplies too.