It really depends on if she has ever used a sewing machine before. It's easier to learn on one of the "teen" models and then work your way up to the models that have all the bells and whistles.
I would look at a Simplicity if she has never sewn with a machine before. They have instructions on how to thread and even wind the bobbins printed on the machine itself and they are numbered....as easy as you're gonna find.
Now, I do have a very small Simplicity that I used maybe a month before I got the hang of it and the hubby bought me a bigger one. You can have it if you want. Seriously, it's just sitting in the closet, and it will be years before my daughter would ever show any interest. (she's 3 1/2)
Other than that, I would look on E-Bay or somewhere like that to get a good deal on a machine that's not going to kill your budget.
Just let me know!