I bought my SS perlicks, shanks, etc on Amazon. Found a pretty good deal there. I forget the vendor, but they had "beer" in their name. It was a combo shank/tap handle/faucet deal. I have 4 on my keezer. I suggest also getting the tap wrench to get the faucets tight on the shanks.
I thought that was going to be too easy:
Google Search Criteria: site: amazon.com perlick beer
Google Results: About, 1,060,000 results (0.26 seconds)
