Which Calculator Should I buy for my mathematics classes? Advice

Links to more calculator information:

http://archives.math.utk.edu/calculator/
A plethora of good sites for all brands of calculators…
http://education.ti.com/educationportal/sites/US/productHome/us_product.html
Calculator support for TI's By Texas Instruments… try the Downloads tab and its drop-down menu

Links to some TI calculator manuals and HP calculators:

  TI Voyage 200 Guidebook - pdf file
TI-89 Titanium Guidebook - pdf file
TI-89/TI-92 Plus Guidebook - pdf file
TI-92 Guidebook - pdf file
TI-86 Guidebook - pdf file
TI-85 Guidebook - pdf file
TI-84 Plus/TI-84 Plus Silver Guidebook - pdf file
TI-83 Plus/TI-83 Plus Silver Guidebook - pdf file
TI-83 Guidebook - pdf file
TI-82 Guidebook - pdf file
TI-81 Guidebook - pdf file
TI-80 Guidebook - pdf file
hp graphing calculators

Note: TI gives permission to copy and distribute the calculator manuals at the linked site.