Just a few weeks ago, I hopped on Cemetech and searched up "finance" into the search bar.
No programs came.
So, I decided to make my own finance program on the TI-84+ CE, "BetterFinanceCE". I'm using TI-BASIC for the programing language of choice, and I already have simple and compound interest down. It will take some time because school (and because I'm pretty much a beginner in TI-BASIC), but I do expect it to be finished at some point. Be sure to tell me your thoughts and suggestions!

Here is the github repo.

You could use celtic and spriter for some fancy graphics.

I'm thinking of adding an icon to the program, and I've been experimenting with Celtic for sometime, so animations are NOT out of the question.

I recommend using Spriter, as it is my favorite icon creating program for TI-BASIC. It's also on-calc, so it's what you could say "portable"