On the wiki it says you can select the new map to obtain map currency. It doesn't even offer me the map tho, is that a known issue or is the currency contained in one of the other 2 maps for some reason? o.0
Edit: Switching to a map and opening the panel again made the option show up ...
Since the February WvW patch these seem to have been (acidentally?) removed as a possible drop (needed for infinite siege). The only way to obtain them now is from lockboxes or crafting, which is why the prices have gone from 2g to 8g, making a single infinite siege cost close to 1k gold now ... (on top of 10.000 player kills).
It is not mentioned anywhere in the patch notes, neither in the wiki. The forum post regarding this bug/stealth nerf has not gotten much attention and I am not sure if Anet is even aware, so I'd just like some clarification.
Forum post for refference with people noticing this rather niche problem: https://en-forum.guildwars2.com/topic/169540-pile-of-recycled-siege-equipment-not-dropping-anymore-since-the-february-24-patch/