To be truthful, unless you live on the coast near fishing docks, most if not all of the fish you buy is flash frozen on the boats it is caught on, and a lot of the fish you have at sushi restaurants is too. Modern technology has improved freeze/thaw methods to the point that chefs cannot tell the difference between frozen and fresh fish.
I buy my sushi grade fish at Whole Foods, they have a section of it, at least they do in Boulder. They usually have tuna, salmon, yellowtail, and cooked eel, which covers pretty much all the bases for inexpensive to mid-priced sushi that I like to eat. I also usually buy cooked crab meat.
As for equipment, there are like 3 asian markets in my town, two of which are inevitably closed when I go shopping, but I always find one open that has everything I need.
Mu old roomates and I would throw make-your-own sushi parties. Everyone would bring some fish and sake, we would provide environment, equipment, rice and nori....always a fun party and people would just make rolls if they wanted, cut em up, and everyone would leave drunk (on bicycles of course) and full!
