I wish I would have gotten into diving a lot younger then I would have bought tanks. I look at them every time I’m in divers direct. You are correct ELLOCO about the buoyancy swing with alum 80’s that most charters provide. I have gone as low as 10lb at the start of a dive and by the time I hit 1500psi I start to struggle to stay at depth and if there is any current it’s impossible. To be good the entire dive I need 14lb. I use alum 100’s every time I can and I’m good at 12lb.
I am surprised at the OW cost Tbird posted. Maybe Open Water Referral / Checkout Dives would be more fun if you are going to pay a lot. Take a vacation to the Keys, most of the dive charters offer the checkout dive portion if you have completed the classroom and pool work somewhere else.