eric5h5: GOG doesn't set prices.
Only publishers can do that, and you rarely find that they set prices differently on different stores.
So if you leave GOG over prices you won't normally find better deals elsewhere.
Yrtti: I do wonder about if it's entirely true, because I can definitely get some games that are on GOG cheaper elsewhere.
I can tell you this much: in brick and mortar stores the dealers have a certain leeway between the suggested retail price
(SRP) and their own purchase price
(=the price they pay the producers for an item).
The difference between those two prices
(the dealers' price is always lower than the SRP) is, where the dealers make their money.
And it's more or less up to them, how much money they want to make
(within certain limits, of course. E.g.: market reality, etc) So, if dealer A buys product X
(SRP=€50,-) from producer 1 for €30,-
and dealer B buys the same product X from the same producer 1, for the same €30,-
then it's up to the individual dealers, how much they ask from their customers.
Basically anything between €30,01 and €50,- will earn them money.
The lower they set the price, the less money THEY'll make, of course.
(the producer has its money already, at that time) So, in theory, dealer A could ask for €45,- and dealer B could ask for €35,-
Both would make some money with those prices.
Only dealer B would offer the customers a bigger incentive to buy from him, instead from dealer A.
Also in theory, it's up to every dealer to go even lower with their end price...however, that will cost them money, of course.
(this gets done, anyway - since it helps dealers to reduce their loss, if a certain item is past its "shelf prime" and the dealers don't have a "take/buy-back-option" with the producer) Now - so far, this was all brick and mortar stores...I'm not sure how it works in the world of online game shops.
However - I'm pretty sure, it isn't so different from the old, analogue ways.
The devs/publishers get a fix amount of money for every key the dealers sell.
But in contrast to the brick and mortar days, the producers
(here: devs/publishers) don't receive their money upfront.
Apart from that, the same main rule applies: the lower the dealers set their price, the less money THEY will earn.
The devs/producers always earn the same.
Now - for sales, additional rules may apply.
E.g.: a cut of so-and-so many percent from the normal "key-price" that the dealers have to pay the devs/publishers, that they can forward to their customers.
But again: the lower the dealers set their prices, the less money THEY make.