BDO now has a central market. It is pretty simple to use. The “Marketplace” button in your storage at the storage keeper now opens the warehouse window, or you can use the “Central Market” button at your local market NPC. Items to sell are listed from your warehouse, and you have to put money in your warehouse to buy things.
If you had stuff listed on the old system, you can still retrieve those listed items and/or cash from sales at the market NPC.
I grabbed a few screenshots of the interface while I was checking it out at the market NPC.