For below $300, I think Yamaha is probably the best option and the E series you mentioned has decent sound. I used them before and I am used to the much higher priced models and found the sounds usable.

But if your friend can spend $600-800, and wants a good piano touch keybed which is very important for some, the new casio privia 330 is the best right now and has arranger features as well. Or the Roland Prelude is very nice as well.