There are some big breeders who might be able to help you out. Just give them a call or send them an email.
Here are a few:
http://bhbreptiles.com/
http://newenglandreptile.com/nerd/
http://ralphdavisreptiles.com/
http://www.jkobylkareptiles.com/
Someone on this site may be willing/able to help you out, if I had a shed that big i'd be more than willing to send it to you, sheds don't have much value (to me at least)