My kids both already have graphing calculators, because they’re enormous nerds they’ve already been required to have them for school, but if you’re still in the market, I have a deal for you. Right now Amazon has the Texas Instruments TI-NspireTM Handheld Graphing Calculator with Touchpad available for just $49.97 shipped when you buy directly from Amazon. (You may need to go to “More Buying Choices” in the righthand column to select Amazon as the seller.) This is its lowest price ever on Amazon, and a good 20% off the lowest I’ve seen elsewhere.
This one is SAT and ACT certified, too, so the kids can use it during testing.
I own three graphing calculators – the original TI-81 purchased 25ish years ago, when it was all I wanted for Christmas (hello, I am a math geek), a TI-83 and a TI-84 plus (purchased when I went back to school to be a HS math teacher and couldn’t find either of the calculators I already owned) – but my inner geek is screaming that we must have this calculator!