Ooof. Let's see.
I can't really reconstruct what I spent on rental gear before I bought my own; let's say about $2-3k. Once I bought stuff, I spent about $6k for essential gear (including wetsuit and drysuit), probably closer to $10k once you factor in camera, boat coat, those dive sandals I just had to have because they have holes to drain water, second computer, second (better) set of fins, pony bottle with reg and other items for solo diving, etc., etc.
Probably about $1500-$2k on various courses and instructor/course DM tips.
About $10k in international dive travel.
Fourteen round trips to Catalina on the ferry at about $1250 total (I like to take the Commodore Lounge on the way back.)
Twenty local day boats at a total cost of between $3-4k with tips.
I've gone through 3 air cards and a Nitrox card at my LDS, so that's another $250 in fills. I don't even want to think about gas or wear and tear on my car.
I'm sure I'm forgetting a lot of stuff. But just those things come to a minimum of $24,000. And if we round up to the 200 dives I hope to make by the end of the year (most of the rest will be beach dives), that comes to at least $120 a dive, probably a lot more. Really makes that $100-150 all-inclusive Discover Dive look like a steal!
I like to fantasize that, now that I have "everything I need," the cost per dive will come down. But who am I kidding? Every time I go in for an air fill, I come out with a new toy. But hey, I make good money and don't have or want kids. What else am I gonna spend it on?