Wow, what are the odds?!
I'm sorry, I don't know where you could find one offhand but here's some info that may help you track one down.
It's a Marvel Comics model kit put out by a company called Toy Biz it looks like. I purchased mine at Wal-Mart a couple (maybe even 3 or 4) years ago. I haven't seen any lately at any of the hobby shops or anything but there may quite possible be some on e-bay, or places like that. There's also a phone number here for Toy Biz themselves that you may want to try and see if they can help you out too. The number is: 1-800-634-7539.
Just a warning: Be prepared for a fair bit of filling. The fit is atrocious and the gaps at the joints are huge. Mine is actually coming along quite well, in spite of that, and I think it will be a really cool looking model when completed.
Good luck in your search. I'll keep my eyes open too for ya.
Ray