My Girlfriend is in the same position... She is in college and paying for it her self (with very little help from FAFSA).
She is actually starting a Dive club at her school... But they don't have much money either...
They might not even go on Dives, Because you don't have to certified to join the club... They might just talk about it and have speakers.
My guess is your Dive club would be a good idea for you to join, unless you have to be certified to join at your school.
Because IMO, your highest expense would be the Classes Unless you want to buy your own gear as opposed to renting it.
Diving is expensive, But school is even more so... And which one is priority? I imagine it would be your education...