Cavendish is usually a good producer in your zone for reliable fruit. It is a shame they are not doing well for you.
For some local proven varieties and some not so common plants do check out craigslist.....average cost per plant is 10-15 US dollars.
Plus as an added bonus a gardener is usually willing to share something else in the garden if you ask.
I have found a few gems on east coast Florida Craigslists including variegates .
Give this thread time and Florida Members will chime on in and maybe they will sell you some extra plants. There are a few members nearby.
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heartland FL farm & garden "banana plants" - craigslist