Other than Gravity Rush DLC, I've never bought any dlc, expansion or bought any MTX except in cases where I bought the complete edition that had all that stuff included. I've never pre-ordered a game either at least not for the pre-order dlc (I've imported some games so that can be seen as pre-ordering I guess)
That said, I buy the base Dota 2 International compendium every year for the last 3 years, once the higher bundle (so like 50-60$ total maybe). I don't care that much about the skins to be honest, I just like supporting the game I've spent over 2000 hours playing and I do watch TI every year.
Slightly off topic but I've only had Xbox gold subscription once during the Halo 3, Gears of wars days and only used a gifted PS plus subscription, so I haven't had either for the last 4 plus years.