I could ONLY see a Sweetums being sold for several thousand dollars at Sharper Image, like the life sized Star Trek or Batman figures they have. And who the heck buys them, unless they're filthy rich?
I don't see why Fozzie would be more expensive to manufacture. It always seemed to me like a shipping size and storage issue. I'm sad about Fozzie, but I can see why a company would want to build a larger loyal base before investing in a Fozzie. That must put Rowlf completely out of the running.
I could see the size being the main problem... not only for material costs, but as you mentioned shipping, handling, storage. Piggy somehow seems to be something that would cost a mint too. I'd like to see where they could go with replicas of smaller characters.... Robin, Pepe, or Rizzo for example (actually, I think I listed all the popular ones). So far there was Kermit, Gonzo, and Animal. And those guys are pretty small compaired to Fozzie, Rowlf, or Piggy
Honestly, I'd like to see the estimates for a Scooter. he doesn't seem that much bigger than Animal. But is he really that popular outside the muppet community to explore?