deadwooddan
The best place to order might be from Powder Valley Inc.
The best place to buy some locally might be from a Traditional Muzzleloaders Organization in your area. Search in your area for a group or club of 'Traditional' muzzleloader shooters.
Search on the internet for your states MLA... in my case I use the Washington State Muzzleloaders Association. In that area they will tell you of the nakes of some of the states clubs. They usually have a stock of BP and will resale it without the hazmat fees associated with shipping.