I don't have the cost, but there were 120 people working at Larian when D:OS 2 was finished, and now there are 250, with another 100 from outsourcing for extra help.
Holy cow is the engine that demanding?
It's a much bigger game in term of mechanics and content, even if a playthrough is said to be of similar length.
DOS2 had 5 origins and 5 races. The skill lines (there was 10) had between 15 and 25 talents/spells to pick from. That barely covers the Wizard's spell list.
BG3 EA will have 5 origins, but 8 races and 6 classes (well 13 if you count the archetype). Release will have more of all of that (origins, race and classes).
