On Walmart where you can now buy this
Texas Instruments TI-84 Plus Graphing Calculator for just $75.67 shipped (regularly $139).
This graphing calculator offers up to 10 graphing functions, advanced functions, and even a split-screen setting! It has an I/O port to connect it with other Texas Instruments products. There are eight display lines and it has preloaded software including interactive geometry software.
This calculator is commonly found on high school or college supply lists so now is a great time to grab one if you have kiddos in or close to either!