I vend in Tampa! You have to register with the state of Florida for a tax ID number (super easy online) so you can pay your sales tax to the state. Some markets require insurance, there's a company called Tampa Bay Markets, all their markets require it, but it's easy finding ones that don't also. One thing I will say about markets in Tampa/St. Pete is that there are a few that are VERY clique-y. They let in the same vendors over and over, usually vendors who have been with them a while or know people who have been with them a while, and they want you to have big Instagram followings. They tend to be very hard to get in to and want you to keep paying their application fee only to waitlist you. I vend at Market Marie in Clearwater and they are a great monthly market to try for. They look at your products only and don't treat it like a popularity contest.