The 99 cent store has sold 4-function calculators for a while. When I saw a "scientific" on the shelf I had to pick it up and look, and I got a real surprise:

Hex, octal and binary conversions. Ten digits. Parentheses. Complex numbers. Coordinate conversions. Deg.min.sec conversion. Single variable stats. For a buck? Really?

I bought one and tried it out. The functions all work, no missing display segments, and the keys all work and are quite usable for rubber keys.

The complex numbers appear to be just for four-function and coordinates, not for scientific functions. You press for example 2nd CPLX 1 a 2 b X 4 a 8 b = to do a complex multiply, then a and b to see the real and complex parts.

The hex mode is 40 bits (1-2 gives 10 Fs) so it understands two's complement. I was impressed and bought several to give out to the coders at work.

Here's what the package looks like:

Package photo

Here are scans of the two sides of the one-page manual (zoom to read):

Side 1

Side 2