>>5978536It comes partially from exclusivity, as previous anon stated. The smaller the production number and the more popular the sculpt/artist is, the higher they can push the price.
The other part... well I don't know. Everything under 1000 USD is still nothing unusual for this hobby. It's all very much subjective and if it is worth the price depends entirely on how much you like a doll and how badly you want to have it sitting in your room.
Basically you gotta listen to reason and be aware or your financial resources.
If the price makes you mad or you have to cut back on basic necessities to finance it, don't get it or you'll regret it.