Where is the least expensive place to go for spring break?

Democrat for McCain · Yahoo User

I have a budget of $500-$700 and I want to fly from Louisville, KY.I want a beach destination that is teen or college student friendly. I went to spring break in Cancun for 5 days, 4 nights last year but my brother paid for it as a graduation gift ($2159, ouch!). I'm in grad school now and I can only afford 1 night at any place.The week is the 2nd week in March.