Check out Mud and Musk turtles, they stay much smaller than RES and Painteds, and will require less demanding setups.
I'm assuming that the turtle you'll be buying is going to be 4"+ in length, since I think that is the law over in the US. For basics, you'll need:
-50 gallon tank
-200W submersible heater
-a decent filter (try to get one rated for twice the size of the tank since turtles are hugely messy compared to fish)
-a light fixture for hanging above the basking area (most people also recommend the use of UVB lighting, aswell as a regular spotlight for heat)
Turtles are very costly, and the setup above is only really suitable for a juvenile, an adult will need an even bigger and more expensive setup.
They really are great animals if you can devote the time and money to it, while I agree that animals shouldn't really be gifts, you could always buy the setup for her and let her choose the turtle.
Well done for doing your research

Paul