Are you talking about the Carolina Canoe Club roll sessions at Farrington Point? If so, most folks have a couple if not a half dozen boats lying around. You can make a post on the CCC list (
http://groups.yahoo.com/group/ccclist/ ) when spring rolls around, and someone might be able to bring some extra gear for you to try out. There's also pool sessions at Pullen Park on Friday nights during the winter where you can rent gear (boat, skirt, paddle, pfd) for the evening to try out in the pool.
If you are looking for flatwater/sea kayak rental, you can try Frog Hollow in north durham. The REI in cary used to rent kayaks, not sure if they do any more. And there's the place on Falls of the Neuse rd by the bridge over the river, can't remember their name (it seems to change every year).