Where does my money go?

Most of it will go to Bethesda. Even if Interplay still existed, they would not get a penny.

P.S.: Gaben will also buy a new pair of socks with your money, and if you buy the whole collection he will be able to afford some nice fishnet stockings.

Gaben takes a cut, but not the whole value of the game. I believe Bethesda gets the profits now because they have the rights to the earlier games.

The current publisher who put it up on Steam. (And to drive this point home, the old Fallouts were actually permanently taken off from Steam and the exact same software was added, but it is called "Fallout (Bethesda)" now, very humbly.) This always happens with games where the original devs don't have a contract on future sale profits. This is why when an IP changes hands, the new owner either cuts the price a lot to generate new sales quickly, or raises it to get more money from those who missed it originally. Bethesda, as expected, did the same with all id software and the Fallout games. Usually small publishers choose the first method to see a fast return in the investment.