Wow. This is just weird. My LHBS (South Shore Homebrew Emporium) has not only recommended a double crush, but they give me their personal tips on increasing efficiency. There are closer shops, but I make the hour and a half round trip because it's a great store with friendly employees. I would like to give your store the benefit of the doubt; maybe there was some problem that they attributed to double milling. I would imagine repeat customers are far more valuable to a small business than a couple extra dollars on grain.