Something like ge-tracker? I always thought it sounded fun to work on something like that, but also a ton of work for a game I'd probably be bored with way before I'd be able to finish anything tangible. I'm guessing there's decent potential for profit though, so that might be a good motivator.

Yep, same basic premise as GE-tracker with higher detail visualizations and fancier stats/feature engineering on top. Flipping to max cash became a pandemic hobby of mine, so I started off with a handful of homerolled spreadsheets/Jupyter notebooks to cover blind spots that I felt GE-tracker was missing, and eventually decided I could make a better version of the same recipe on my own.