It's interesting to see that many of the under 30 group had dad's who needed a buddy. I know my son is in this category and he could in no way afford diving if it weren't for his dad.
To me the cost is insignificant. I get to and have spent some fantastic quality time with my son during our ten years of diving.
It started that way for my dad and I but due to his work schedule he hasn't had a chance to dive in a while. I've been able to keep logging dives by diving with folks from my LDS (including my boss).
I used to go on dive boats with my dad when I was a kid Between age 5-10. He however, stopped diving because of family and especially work. At that time I was very interested in taking up the sport when I would be old enough to get certified, but when I was old enough, he was not diving anymore. I took up golf (another expensive sport) when I was 14 and played on the high school golf team. When I went to college, I stopped playing golf competitively. I ended up getting a decent paying job in my Senior year of college which provided me money to do things that I could not do before. I was lucky that I was still living at home and not paying a lot of expenses including rent. I decided to take up SCUBA and get certified at 23 and bought my dive gear later in the same year. I also got to go diving in Hawaii and the Carribean within a year. I am now almost 28 years old and have logged almost 85 dives. I am hoping that I am still doing this sport when I am 70.
Working for a dive shop can help with those expences, plus the perk of free air (depending on the boss)