I have the B3, I wouldn't get the B2 unless you live in a very windy place, which Sarasota is not. I teach on the B3 in SE Florida and it's perfect. It will give you a good pull in 15-20 mph that will actually let you feel what real kite power is like, whereas the B2 doesn't really pull at all, it will just teach you how steering a kite works. These kites are super super super safe (just let go if you get scared) so don't worry about that.
My actual advice, is to just find a cheap 3m trainer kite on ebay, they are fun to play with and teach you how to steer a kite in the sky, but you still have to take lessons afterward which will cost even more money. Once you've been on a full size kite (after a few hours of flying the trainer) you won't ever need to be on a trainer kite again, so they are kind of useless unless you plan on teaching friends.
It may be worth it to just take a lesson with someone that has a trainer kite and not buy one at all