When I was a frog for Halloween, I made flippers out of paper that wrapped around my ankles and wrists, if that makes any sense. It worked, but it depends on how durable you need your flippers to be.

Could you be Pippi Longstocking?

Or make some kind of tail and use the frog headband with some creative license and be a lizard?

I was once a pirate with cropped pants, a loose blouse, and I made a patch out of paper, and a newspaper hat with skull and crossbones, and carried a stuffed parrot.

You might be able to throw together a gypsy costume, but I'm not sure if that's P.C.

You could be Mother Goose, like me--I got the idea from my aunt, who's a librarian, and she dressed as Mother Goose last year for work.