Steam-powered games? What are you talking about?
GOG sells DRM-free games. So if the game requires Steam as a DRM manager, then you won’t find it on GOG, obviously. But, news flash, Steam isn’t synonymous with “PC gaming”, it’s just another service. Which is the whole point of my post, to say “Hey, folks, Steam isn’t the only player out there”. Apparently many people think that way because we get posts in the Gearbox forums on a regular basis talking about Steam sales. You don’t have to wait for Steam for discounts, you don’t have to buy from Steam because a publisher like 2K uses the service as a DRM manager. If you buy from Green Man Gaming or Gamestop, to name a couple of examples, you’ll get a Steam code.
And, yeah, “best prices” sites can be more or less useful - but they also tend to be flawed in their searches. It’s a very good idea to spot-check, to see if the price is really the lowest by looking for yourself. So, you don’t HAVE to search “manually” (as though that were some kind of huge chore), but it’s a good idea.