If WM has it, the price is almost unbeatable anywhere. On the rare occasions someone has a caliber I shoot cheaper than them, I try to buy ahead a bit.
A few times a year I head down to AZ, and Prescott is on my way; I stop at J&G, whose prices are usually not lowest, but since I'm passing through anyway--no shipping makes it cheaper. Last week I spent over $600 on ammo there. That should last me several months (6 or more I hope) and was enough cheaper than Vegas prices to pay for gas & meals on the trip, even at today's prices...