Amber for sale at Rare Material Traders

Something strange just happened, when i checked trader i saw Amber for sale for 1,1k. When I closed and reopened trader it was gone again :s So is Amber for sale now ?

It probably built up a stock which was gone the moment after?

Maybe, don't have experience with traders which ran out of stock.
But isn't 1,1k very low for it :s ?

The rare material trader will have stock when players sell to him. So if someone sold 10 to the trader for whatever he is giving at the moment, they then are open to the public for purchase. Apparently while you were viewing, someone bought him out.

Keep in mind that the price that is offered in game by other players, especially when the trader is out of stock, will not be reflective of what you will actually pay to purchase from the trader.