I certified my son @ 16, he is now 18 and nearing the end of his 3rd season with >100 dives total, we expect to hit 40 for the year tomorrow.
He has contributed about $800 (BPW, computer) to his kit from his savings, the rest has come from me - tanks, regs, wetsuits, lights, etc.etc. On top of that you can add the training - OW, AOW, Deep, Nitrox - the dive trips - Tobermory, Victoria, Cape Ann, Cuba - the boat dives (how many ?) - the fills, the gas to the dive sites (St Lawrence is an hour away) or the quarry (1/2 hour + $10/PP), THE GRUB! (growing teenage boy LOL)....
I am not being a martyr, it is what it is, but this can be an expensive hobby to get going in when you are paying your own freight - which he does not have the resources to do, like most young people. He just started university so it will be a while before he is flush enough to do much diving on his own nickel. Of course, the good news is that we now have all of our own gear (everything we NEED, dry suits would be nice LOL) so it has now dropped to fills, gas, and grub for local diving.
So long as he is a good dive buddy I`ll keep him on the payroll