I don't know where in Florida, but I know Jean Pattison is based there, and she definitely breeds Jardine's. I don't know if she keeps an open or closed aviary, but you might contact her to start. Even if it's closed, I'm sure she can direct you to Florida bird stores to which she sells her babies. I'd be surprised if you couldn't find a Jardine's in Florida to meet in person.
I almost chose a Jardine's instead of my Cape Parrot-- they're both the larger two poicephalus and in some ways are very similar. The tend to be on the quieter side (although they can definitely be loud and have very high pitched calls), although if you were considering a mini macaw, I don't think their volume would bother you. Pois tend to be very smart but also very stubborn. The big thing that scared me away from Jardine's however, was reading about what is commonly referred to online as "J'attitude," basically a term for their terrible two's/adolescence period. I'd definitely do some research about that.
Regarding talking ability, no parrot is ever guaranteed to talk, so if that's very important to you, you might consider adopting an adult who already talks rather than a baby. Lola didn't talk until she was over a year old. As for dietary needs, from what I've read they are like most parrots, with the one exception of the calcium that you've already mentioned. Calcium can be challenging to get into a bird's diet though-- the Feeding Feathers group, for example, does not recommend ever supplementing outside of pellets (there was just a thread on this in the Facebook group if you're interested)-- so you'd probably want to make sure to keep your Jardine's on a high quality pellet and make pellets a significant percentage of the diet.