I am assuming that you mean Avalon and not Two Harbors, right? You might actually want to look at some of the dive packages that include transportation, lodging, and diving. I usually stay at the Pavilion Lodge because it is convenient, but I don't know what your price range is. As for dive shops, there are two - Scuba Luv and Catalina Divers' Supply. Scuba Luv is in town, and the owners are very nice. You can do trips off of the Prince or King Neptune and dive off of Casino Point. Catalina Divers' Supply is on the pier and out at Casino Point, but the last time I was out in Avalon, they were still working on reconstruction of the pier and that shop was closed.