I usually just try to buy all the DLC at once, if it's something like Saints Row or Fallout. I think additional content like levels and missions and stuff like that, is a great idea for any game, but stuff like cosmetics, I'm not exactly okay with (unless it's something like TF2 where buying cosmetics from the store is one of the draws).
I feel like Payday 2 hits the right balance. There's lots of paid DLC, new levels, characters, weapons, but there's also constant updates adding the same sort of thing for everyone. I've bought my fair share, but I've never felt the need to, y'know? It's something you can't get for free, but if you don't want to pay for new content, then that's okay, because new content is always being added for free, just like it is for money.