You're probably right about the complexity but you're missing one thing. The interchangeable 'Sideshow Maquette' label.
Without that useless naming scheme, I never saw this being charged north of $600 USD. Well at least I hoped.
Because examples of higher priced 1/4 pieces are pretty much all 'Sideshow Maquettes' or Maquette adjacent, such as the Thanos, Doomsday, Rogue, and Magneto. And supposedly the Deadpool should've been called a Maquette according to a remark made by a Sideshow rep on Sideshow live, so I'll include Lady Deadpool with him as well.
The only outlier that I can think of is the new Thor Premium Format, which looks just as complex and is priced just as much.