I spend about 1000 euro's this year. That is inclucing flight, renting an RV with 3 others, entrance ticket, camping ticket, beer and food and general spending money. If you go with a small group it becomes less expensive. Cost of beer and food is cheaper compared to the UK or Holland.
Sebring is about an hours drive from Orlando by car, little longer by RV. Easy drive. Closeby of course disneyland (to convince the wife), universal studios, bush gardens in Tampa. The everglades, not to forget kennedy space center and if you are lucky, you might even get to see a space shuttle launch like last march.