Today I got myself two scientific calculators:

• Casio FX-991CW Advanced Scientific Calculator (eBay)
• TI 36X Pro Scientific Calculator (Amazon)

One graphing calculator:

• HP Prime G2 Graphing Calculator (eBay, supports CAS)

And a few books about how to use them:

• How To Use A Scientific Calculator: The Ultimate Companion for Students, Professionals, and Hobbyists
• Casio fx-991EX Classwiz for High School Students
• The Casio fx-991EX CLASSWIZ Practice Examples
• Calculus on the TI-36X Pro Calculator
• TI-36X Pro Scientific Calculator Practice Examples
• A Level Mathematics on the Casio fx991EX Algebra
• A Level Mathematics on the Casio fx-991EX Trigonometry
• A Level Mathematics on the Casio fx-991EX Calculus
• A Level Mathematics on the Casio fx-991EX More Calculus

If you’re interested in such things you might like to check out Developing a Scientific Calculator Easier for Everyone to Use, the story of the Casio ClassWiz models.

I also considered:

• Sharp EL-506TSBBW 12-Digit
• Sharp EL-W516TBSL 16-Digit

On my iPhone I have:

• NCalc FX – NCalc Scientific Calculator
• Calc84 – NCalc Graphing Calculator 84