A lot depends on where you are in Fl, Florida is not a cart friendly state, in the respect that you are limited to “frankfurters”  they allow you to sell smoked sausage also , but grilled onions and peppers are a no no. 

To make any money on a cart in FL takes a very good location, so I would look at my finances and revisit the B&M idea, second choice would be an MFVD.

The largest and most powerful lobby in Fl is the rest/hotel lobby, thus the restrictions on carts.

As far as used carts, there are hundreds of them in FL for sale.  Go back to craigslist and list in the want to buy section, great carts around here sell for 1500 or less I have seen them for less then $1000 and looked barely used.
I can’t sell mine because it is an oldie but goodie, because of all the newer carts available, but I,ll turn it into a planter before I sell it for less then $1000
Another option is shows festivals etc,  much less restriction and a different set of rules. For example a  temp’ show vendor needs only one sink and the commisary rule is generaly over looked, many shows are sponsored by civic groups, non profits, and Churches, wich also have a different set of rules and are usually given a pass by the regulators.  I am currently compiling my 30 year list of shows in Florida, and as now have only completed 3 months . 417 shows in July, 409 in May, and 507 in March and that just scratches the surface.

It is hard and sometimes mind numbing to become a vendor, but once you get there, it is a great and free life style ,and worth all the BS.  Good luck