Buy used, make sure they have a title in hand and buy name brands! Can-am, Yam, Polaris ext.
couldnt agree more. The brands you mention are chinese and parts issues will arise. Look for clean 2-4 yr old stuff and you will be much happier if you do start riding and enjoying this hobby. As also stated, south florida lacks badly in riding areas. The closest FAMILY riding area to you is Dirty Foot Adventures and that is likely about 4hr drive one way for you. Most riding areas people mention are just places they are getting away with it for now but if you dont own it or you dont have written permission then ridig is illegal of course unless it is in a park like croom, motoplex, Ocala Nat Forest or DirtyFoot...etc.
Honda is usually the most bulletproof quad out there for beginner size quads..ie..trx90, trx250, trx300ex, trx400ex.
Good Luck hope this helps.