Try Allison Landscaping here in Cincinnati. I could have sworn I saw some rather large BBB's, around 7ft. in their inventory.
(513) 922-1313

Here is a link that might be useful: Allison Landscaping Address and Phone

There's a nursery on Kenwood road in Cincinnati, near Blue Ash -- something Farm? -- where my mother bought a very large, 7-8ft magnolia that I believe was a Brown Beauty. They delivered it and planted it, but they planted it too deep (or too shallowly) and it died. So they came out and replaced it with one even larger.

Natop's in Mason Ohio & Florence Ky. still should have some in their inventory!!http://www.natorp.com/gard.htm

They usually run about $100 for a 5gal.

Ky. Joe