How is the default price of an item in GTM determined?

When I try to sell an item through the Galactic Trade Market, some price is automatically assigned to the item. I can then change the price, but I think many players will keep the default one.

How is this price determined? Is it somehow based on the state of the economy on the server? Or is it a static price (maybe based on the price when selling the item to a vendor)?

It seems like the default buyout price is 450% of what a vendor will pay. Deposits vary from 22% of the vendor price (6 hours) to 68% (48 hours).

I have no evidence, but I would not imagine the price would vary.