simplyrugged.com has basic, durable, reasonably priced belts in 1.5" and 1.75", ready for internet order, and pretty quick on delivery.
Stepping up in price categories, andrewsleather.com has some very nice belts, but you have to call Sam to order, as his site doesn't have order capability. I was drooling over one of the belts he had in his shop a while ago - tigershark leather. For a demonstration of its toughness, Sam scratched it with my car keys - and didn't leave a mark. But I'm just not in the market for a $400 belt just now.... one of these days, though.
Sam's non-exotic belts are much more reasonably priced, but he does have some interesting exotic leathers (belts and holsters, both).