It sounds like the $500 was selected to cover the standard change fee for 2 international tickets. It shouldn't be difficult to find good fares to the Caribbean during the summer as it is low season, especially early and late summer. Curacao Marriott is $143/night or 150K points for a week, GCM RC is 360K points for a week. I am sure there are other Marriott properties in Cancun (if you like that environ), St. Kitts, BVI, or USVI that have award availability and some excellent prices for June. I would think outside the box and not limit yourself to Jamaica.

To GCM from DCA economy tickets run $581 and first/business runs $1539, to CUR economy tickets run $633 and first/business runs $906, and to CUN economy tickets run $556 and business runs $823.

You may actually come out ahead in the long run. My advice would be focus on the solution. Good luck.