Do you have AAA? Have you given them a call? Also, have you checked Travelocity or the other travel sites? Another possibility, have you called Disney directly?
These options may yet make it possible to visit WDW. I wouldn't discount Dolphin, either. It actually is on property. Check around on this site, there are discounts available for certain groups. I'd call them directly, too. And, of course, if there is availability at Coronado, that is a nice resort.
...I used to visit Port St. Lucie often years ago. Pretty place.