They must have a team of developers working on that site. It is not just a script you can buy. Must have lot of hard work put in place. Even if you buy a script like that you need to still hire full size team to compete against them. Hard work but sure to payoff -- There are lot of armature photographers and there are a lot us willing to pay for the photos.
Looking for it as well the only i found is a clone of theme forest . com site which is also not too bad