The advancements in kite tech make it pointless to use those kites. The amount of time and frustration they will cause nullify any savings imo. If you absolutely must put them to work, take them south to Aruba (25-35mph winds daily). Its a cheap direct flight from MIA. Our windy season is about to end due to thunderstorm/lightning (all the wind comes with t-storms in the summer, for the most part - unless we get a tropical storm or hurricane). That is why a previous poster posted that video.
Be aware Miami is abit of a hostile place to learn kitesurfing, although the physical conditions are near ideal. Crandon is wonderful - but heavily regulated. You need to get IKO L3 certified to ride regular there, but you might be surprised how hard that is to get to when first starting out. Lessons are only affordable thru L2 imo for the simple fact you need alot of practice to consistently waterstart, edge, go upwind, jump, transition, etc. (all L3 requirements) Its impossible to do when someone is charging you $100/hr - unless you are a millionaire who can bankroll 40-50 hours, which I doubt since you are recycling ancient kites. The entire process takes a full season, judging from others I have spoken with and my own experiences.
The Keys are currently easier going about it all and a short drive (1-2 hrs) - BUT, the beaches (if you can call them that) are not soft white sand like Crandon and you will need booties.
If you get into it, message me, its always easier with a second person for launch./landing and I go to KB alot. DO take lessons after you get some experience with a trainer flying, body dragging, etc. The early lessons are the most worthwhile imo (safety, gear info, posture/form,tactics.etc.), once you are up and riding at least downwind, Youtube can actually teach you quite abit.