T.Z.
travelzoo.com is a great site for deals, if you watch it you might be able to get Cancun/Riveria Maya for a few days for that price. We booked the Iberostar beach resort, all inclusive for about $89 a night a person and kids are free. There are some more deals for that particular resort chain on this site also, I ended up saving $150 by booking thru them. If you go soon, your kid would fly for free also. http://www.iberostar-board.com/boards/index.php
Let me know if you find something there is also a coupon code on www.retailmenot.com for spiritair.com, although they charge for baggage now and seat assignments, We are hoping we won't have to pick our seats ahead of time I don't want to spend the money on that too.
I am going in Oct. with a 5 yr. old and my 20 mth old.