If you haven't tried start with the Fish Finder
http://www.dogfish.com/brews-spirits/fish-finder.htm
I'd also recommend if a place is listed as having it ask them, most places put it behind the counter.
You can also email your distributor for Dogfish, that's found here
http://www.dogfish.com/company/distributors/our-wholesalers.htm
Good luck finding it, took us some time, and it isn't cheap. We're currently setting up a vertical tasting of 120 if I can get my stupid family on the same page we have like 7 bottles which would give us a healthy sample, I was thinking of doing every 2 years but even at 1year increments it should be interesting.