Yes there is, it's for all servers so there won't be any dead economy's. You can do the basic buy stuff out or you can do an item search in the trading post and put down an order (sort of a back order). Some one can come along and see you want the item they have and they can sell it to you for the price you set. Or the person who wants to sell something can just put their own price and wait for someone to buy it.
I don't think it's to hinder scammers. They will find ways to scam people no matter how things are done. If things can change hands scammers will be there trying to prey on the less savvy. --- It took longer to load the match then it did to beat you....
It's not an auction house as such - it really is more of a trading post, in fact as well as name.
You post an item, and the price you want - there is no bidding for higher; once someone accepts that price, the item is sold to them.
When you want to buy, you have to pay the asked prices, or not (and hope a lower one comes along).
The only regulating of prices will be the players. You can TRY selling that sword you got from an enemy for 50 silver, but if everyone else is only charging 10 silver, don't expect anyone to buy yours. (Also, if you try selling a 10s sword for 50s, then I'd imagine even buying from the merchants, directly, would be cheaper.) I'd imagine prices might not be "set" when the game first starts, but after a while, you can just look, see what other people are charging for a given item, and base your price accordingly. (The same? Maybe a bit more, hoping it's bought once the other one is sold? Maybe a bit less, to get it sold sooner? All up to you.)
You can buy or sell from anywhere (there is a menu icon to bring it up)... BUT, you must go to a Trading Post location to receive your items/profits. --- "As the good archmage often admonishes me, I ought not to let my mind wander, as it's too small to go off by itself." -Danilo Thann