Texas Instruments TI-83 Plus Graphing Calculator for $84.99 after this $15 rebate. Add this Pen Filler for $0.38 to apply coupon code 11525859, so the total comes to $60.37 shipped after this $15 rebate. Here is a screenshot before the $15 rebate for your reference. Note that the purchase has to be made by 9/19 to qualify for the rebate. Most places have this graphing calculator for about $99.