There is NO way to offer the alpha or beta below the price people had to pay during the kickstarter. That would be screwing the people who initially supported them
How charging less in steam is screwing anybody? They pledged $90 and getting exaclty what was promised one way or another.
And more importantly Kickstarter is not a store, you are crowfounding a project, not pre-ordering a game. You can give them any quantity of money, even just a dollar, if they decided to support the game with $90 it was their call, if some of them misused it as a way to "buy" an alpha is their own fault
Why are they entitled to maintain the "price" of the alpha anyway? And at the end of the day that's the money they decided to give, if it goes on early access for $90, $10 or $1 it doesn't affect their pledge in any way, is like buying a game and complaining when is on sale, except that they didn't even brought it, they basically donated money to produce the game, whatever they got for a pledge is more a freebie as a show of gratitude from the creators than something you brought. Are you seriously telling me that if Larian charge less than $135 for early access for original sin you are going to complain?