Oh definitely a pair of mud turtles or musk turtles! These are the 2 turtle species that stay very small. This makes them much easier to house and care for than sliders or painted turtles. Plus they look cool!

I'd name them Bonny & Clyde or Micky & Mallory!

Check out the turtle shack for affordable babies.

http://turtleshack.com/store/index.php?main_page=index&cPath=1_6

Any other turtle would require a larger tank eventually. That means bigger filtration systems, heater, etc. These guys stay very small.