I bought most of my stuff used being a student at the time buying for myself, my wife and trying to raise two kids. If you look you can find some pretty good used gear from people who are upgrading and most of it’s in good shape. The only thing that we didn’t buy used was computers. After years of dive tables the computer was worth it. Keep in mind that if your only diving a couple times a year the rental cost may be as cheap as the servicing of the equipment (highly recommended). If your diving regularly it make sense to buy it all of it. Craigslist is a good source and if you find the right stuff you can have it serviced as well as people at the dive shop upgrading. I bought our regulators, paying the dive shop service + $25 to evaluate the regulators. The person I bought them from was happy to work it out this way and we dove the regulators for 10 years until we couldn’t get parts.
Lot’s of ways to be frugal and get safe good equipment, just and I can’t stress this enough get to know your dive shop. The good ones will take care of you and help you on your adventures.
I love being underwater, so it is the best hobby you can have. Congratulations on your adventure.