These days you've just got to shop. The last 500 I bought came along with a pistol. Before that I bought from J&G when I was in AZ-I didn't get all I wanted but I got what they had in stock. The time before that I bought off GunBroker. Locally, ammo is expensive and often out of stock. Get a list of sites to look at and call before you order; you don't want to be backordered in this market. I've got about 4 different companies I like to stick with but lately I've had to buy from others.
If you're curious about a company post a thread and ask before you order.
Price total will depend on where the ammo is being shipped from. I get most of my surplus ammo from AIM. . If I buy from Century the shipping is cheaper but because I live in FL I have to pay 7% sales tax.
If you live near a Cabela's, they now have .50 cal plastic ammo cans with bulk ammo of many different calibers, both pistol and rifle. they charge a decent price, and the ammo cans are well-built and strong, with a waterproof seal. You might check them out.