For what it's worth, I bought a piece of Starboard from Cabelas. Normally I would look around locally, but I had a gift certificate. It was pretty painless to have UPS drop it off at the house though. Something to think about in case you have trouble finding it. Unfortunately, I'm not sure about finding the dimensions you're looking for. Cabela's -- King Starboard Marine Grade Polymer
Yes, bought mine up in baltimore from Total Plastics, Inc. Located in east balto just off the 895 harbor tunnel road at 5424 Pulaski Hwy. Phone # is 800-492-4695. They have all different sizes and thickness and will cut it to size while U wait.
Hey Jerry - Give Harbor Sales a call. They're over on the Eastern Shore and will deliver to your house. They have the best prices that I have found anywhere. You will need to purchase a full sheet ... which is 54" x "96. I'm guessing that you could sell off all of the extra material that you have left over, after your project is complete, to someone on this board and recover some of your costs. I've bought several sheets of 1/2 inch from Harbor over the years and they are great to deal with. Post a picture of your project when you're done. Bob