tman,
I'm assuming you are talking for concealed carry. I use my regular dress and work belts. When I select a holster I just make sure that it will attach to the belt properly, and since most will work on both 1 1/4" (typical dress belt) or 1 3/4" (typical work belt) this has never been an issue for me.
Most holster companies also market a line of belts that work with their holsters, and I'm not saying that they are not worth looking at, but I figure that if I can buy a nice belt with my suit or dress slacks why reinvest in something else.