The ti-83 + is a good one in my opinion.
I have come to the stage in my math studies that a need a graphic calculator. Money is not a problem but with such a big range I am not to sure which one would be the best buy. Any recommendations would be welcome
TI-83 or 84 is a quick learn. the 84's newer OS has a "pretty print" feature which many students prefer. TI also has a new TI-Inspire which graphs in color.
Graphing Calculators by Texas Instruments - US and Canada
Some folks swear by Casios, but they're not as widely used in classrooms as the TI models.
Graphing Scentific & Financial, Basic, Fraction, Printing, Calculators | CASIO America, Inc.
and, free graphing programs for your PC ...
Graph
GeoGebra
http://math.exeter.edu/rparris/winplot.html