You might try looking at this that I found:
http://www.boatcoversdirect.com/boat....php?styleid=0
http://www.ttopcovers.com/
http://www.websweeper.com/php/boat_covers/bc-044.php
I also saw some links to E-Bay and Amazon for covers for boats with T-Tops.
Hope this helps.
I got mine from cabela's but they didn't have anything for T-Tops that I could see.