In my personal experience, professors will say Ti-83, Ti-83 Plus, Ti-84, Ti-84 Plus. Some professors may specifically mention the updated colour versions as well, but let me tell you:
Professors do not EXPECT you to use a Ti-83, most times. The 83 is an out of date calculator, and their lessons will likely revolve around updated versions of the 84's firmware. So, if you're wise I would buy an 84 plus and update it (free and easy to do, though it is a little finnicky. I had to try ~4 times on my 84 Plus which was quite old).