I always liked Casio for scientifics. They were cheap (<$20), well featured, and last a
long time with their dual solar/battery power. I had one, fx-115s, go through all four years of high school only to lose it the second day of college. It had this over-the-top flip lid that covered the face when not in use and angled the face a little for better viewing when opened. That, and you never lost the cover since it was hinged to the calculator (or you could lose the whole thing, like I did).
Oh yeah, there's that ~250 functions, complex math, basic statistical calculations, etc, etc, if you're looking for that sort of thing.
