The current Steam Early Access price is the release price of the game, for both digital and retail versions.
I do not know the contents of any contracts, and am not speaking for Larian in this, but given the available information, it seems obvious that regional pricing was necessary to get distribution deals. Larian would have looked at what it would take to do it themselves, and determined that either using distributors / publishers was the best option despite the restrictions required, or it was the only option since arranging localized retail distribution from scratch was simply not feasible.
Thank you for your answer but I'd really like to hear from Larian on this issue. It is really important for a lot of us for we feel cheated with regional prices. To pay 40 euros for a game that costs 40 dollars on the USA while having 1/3 the average US sallary (according to wikipedia) is preposterous.
Also take into account that Dragon Commander doesn't have regional pricing on GOG. It's 40 dollars everywhere.
One thing I've always liked about Larian is their transparency. Of course business issues are more sensitive than development issues but this is such an important issue for a lot of people that I'd really like to know some more information about it. For all I know right now Larian doesn't enforce regional pricing and it is just a misunderstanding with GOG (hopefully).