er...i do believe it has a 3/4" barb, and a 5/8" barb (thats what heatercore4u listed anyways). am i wrong, or did you goof??
as for cost, i asked my local Autozone and they quoted me $26 special order. it was on their site for like $18 or something. *shrug* i dunno what other stores sell it for. id say $25 or less...anything more and youre paying too much.