Not in Florida, but live in a similar climate (very hot and extremely humid)
The chickens that do best in hot climates are any breed that's small bodied and has a large single comb, that said, with the right setup you can make most breeds work. If you just want a highly productive heat tolerant bird, white leghorns should do well for you, but if you have your heart set on a particular breed as long as you have the right setup you can probably make it work
Your monthly costs depend heavily on the number and breeds of the birds you have, what you prefer to feed and what it costs locally to get it. I could run some numbers for how much I spend a month but that really wouldn't help you at all. My flock is not the same as yours nor is how I choose to run things necessarily how you will choose to run things. Also remember that chickens require a significant amount of money upfront to get started with the biggest expense being a coop. That will run you a couple hundred at a bare minimum and while you certainly don't need it to be fancy, it should be larger than you need, extremely well ventilated, and secure as fort Knox as everything loves chicken. Not having a quality coop will bite you and hard. Minimum size is 4sqft of coop space, 1sqft of roost space, 1sqft (although I'd strongly recommend bumping it up to 3sqft) of ventilation and 10sqft of run space
per bird. I'd strongly recommend planning a coop large enough to house more birds than you plan on getting as chicken math is very real and you will eventually need to add more birds as your flock eventually gets older and slows down laying. It's hard to give them too much room but giving them too little will only lead to trouble
Cost per bird depends on breed and your local market, same with egg prices, I would strongly recommend asking in your state's thread. You can also provide more info on what you want out of your flock and how many birds you want and we can give you some better answers although again, it really will depend on where you get your supplies from
Most importantly, welcome to byc! We're glad to have you here and feel free to hang out and ask all the questions you need to!
