Casio FX-115MS Scientific Calculator
With a natural textbook display and over 279 functions, the FX-115MS is hard to beat. It can solve linear equations (not symbolically) and also uses solar when possible but has battery power when solar is not available. It has great aesthetics too. It does not support RPN, but it is otherwise a fully-featured engineering calculator at a low price with great reviews to boot. Definitely don't forget to check this one out.