Pretty sure you can get them, they just don't call them that any more. Most places now sell them as turtles, usually in the reptiles and insects sections.
yeah you can still buy them in the country.
Red ear'd sliders you cant.
Due to the fact they are living and breeding in the country now.
Either reptile centres of LFS's can sell terrapins.
Just make sure what you know about the specie you would like, and its care.
As most terrapins can grow to a good size, and are good Biters