By standard 2ft do you mean a 10 gallon? If so, you can get one musk turtle and nothing else.
I recommend at least 20-29 gallons for a turtle tank that has livestock, otherwise you can put in small guppies or ghost shrimp for your turtle to chase down and munch on at his leisure. Mine doesn't even want to eat live food, but rather prefers veggies and the plants in my tank. Occasionally he'll pick off a poor shrimp but otherwise he leaves them all alone.
I say you build a tank as opposed to getting one, it will cost around the same with shipping minus the materials and labor, however you can build it long and shallow, as opposed to short and deep.
The water level needs to be at least 10 inches deep, but no deeper than 30 inches.