i don't have first hand experience but.......the guy working on his boat next to me, just replaced his teak and holly sole. He spoke highly of a place in Annapolis call Exotic Lumber. Not sure of their address or exact location but he seemed pretty happy with them. I think he said he got a 8'X4' sheet for around $250.
This is a project I'll probably undertake in the next year so if you don't mind posting what you find I'd appreciate it.
World of Hardwoods
Used to be behind the 84 lumber off of rt100 where you can watch the planes land at bwi.
Now I think they moved to over near GnM crabcakes (hammonds or hollens ferry exit off beltway)? You'll have to look them up if you want to go there. They have marine plywood too as well as al kinds of weird wood.