Yes, you have to have a class III for selling any wildlife. In other words, any animals not classified as domestic.
It sucks, but $50 to cover your bum from incidents like this is well worth it.
It says on the fwc site that it is required for sales of all wildlife not listed...so it sucks that you misinterpreted it, but it's there :/
I even listed my rats on it just to be safe.
Yay government being all up in your business. (Sarcasm)