You might try Vista Cay. It is a brand new condo style resort with a nice pool.
It likely be at the top end of your price range, if you can find it for a bargain. It isn't a timeshare, each unit is individually owned. But if you travel in early May, you might get a bargain.
Try going to VistaCayRent.com. You can make an inquiry via e-mail. You type in some info, and then it sends to many owners... who will then respond with a quote via e-mail. Prices can be negotiable. If you find something close to your price, e-mail the owner and see what they will do.
I think that you'll get the nicest pool in your $100 price range by looking at condo complexes.
The other option is to try Priceline in the Seaworld/Universal or OCCC areas.
Good luck!
Lisa