Stinkpots are very good climbers. I would keep the water level at least 6" below the top trim on the tank.
EDIT: Vicious beat me, lol.
I'm not sure where you're from but take a look at this link and see if there are any reptile shows coming to your area. I can almost guarantee you could fine one at a show. I bought my adult female stinkpot from a show for $20 bucks
http://www.aquariacentral.com/forums/showthread.php?t=188115
And don't be afraid to order one online. They're very easy to ship and don't need to be kept in water during the shipping process. Just don't purchase a baby. A juvenile that is at least a year old to an adult is what you want to be looking for. The Turtle Source always has them for sale but some species can be a little pricey on that site.
http://theturtlesource.com/turtle_inventory.asp?cat=333&id=100200326