Oh, I don't know. Browsing the Games Workshop website for the first time will give you a heart attack when you see the prices, and considering what you actually get for your money the hobby is a bit absurd. But you have to put it into perspective.
If you stick to skirmish games instead of full-blown army battles requiring hundreds of miniatures, you can stay in a manageable price bracket. Realistically, you won't be playing many large scale battles anyway. Nowadays most people seem to prefer quicker games that don't take up an entire living room floor...
Then if you pick an off-brand game system (ie non-games workshop) you can shave another substantial amount off of your expenditures. I bet there's any number of rulesets you could download from the Internet for free (and I don't mean pirating it).
If you are in it to paint miniatures, you won't be buying many miniatures at all since painting takes time. And painting equipment isn't all that expensive.
I you do what I do and mainly make minis of your own, the cost is close to zero, or at least negligible, depending on if you work digitally or with polymer clays.
The main issue with miniatures is that they are plastic crack, and you will inevitably end up buying ten times the number of minis, games, accessories et cetera that you actually need. I went through a pretty severe hoarding phase myself when I got back into the hobby a couple of years back. Now I have an entire kitchen cabinet stacked with literal piles of miniatures from every manufacturer under the sun- that I hardly ever use or even look at.
