It's 25 or 26 years since I started keeping fish. I have no idea how much I've spent in that time.
I have had a number of tanks
60 litre which finally sprung a leak and was replaced
54 litre, which replaced the 60 litre and I sold when the kitchen was altered and there was no room for it
125 litre which was replaced when the bracer bar broke
180 litre which replaced the 125 litre (though that was a combined birthday & Christmas present from my mother)
Several 25 litre tanks - the first was a quarantine tank which became a betta tank; the second was a new quarantine tank; the third was a replacement for the betta tank because the first didn't have an option for a light; the fourth because I liked it better than the third.
Several filters and heaters over the years.
Gravel/sand
Lights
Plants - first plastic, then silk, then live
Fish food, dechlorinator etc
Fish.
I hate to think how much that adds up to. And that's just with a few tanks. Members with a lot of tanks would probably spend as much as me in just one year
Edit to add lights to the list after reading it in Cydeth's post