The offers and the marketplace ruins the usal trading curses by the following facts.
The time that resources are offered is to low and gain dumping prices, because of the market fee after you get it back after 3 days.
And there is no "Edit Button", when you just missclicked you lost allready 15% of your resources. Example you choose Metal instead of Cristal.
I think it would be better, when the time of the offer will be increased. Otherwise the marketplace will be useless later in the game.
When an offer with no result returns there has to be no market fee or a less market fee.
I know the most fleeter will scream about that, but when you have resources leigh on the market and you can't use them they are totally useless.
So miners have to think about loosing 50% or useless 100% on the market. (maybe for 7 days or longer).
That's fair enough for both.
The "Edit Button" might be a great feature as well, because you can lower your offer to gain materials.