Really cool stuff, I would (will) surely use it :)
Small suggestion:
the price amount, could have some formating, so you can clearly see what's the price (1000000 > 1 000 000 or 1.000.000).
the inventory scrollbar, it's browser one, what about adding scrollbar from l2 - ofc if it's not a big deal.
the monster spawn on the map, if I'm not wrong once you select npc to be spawned, you can spawn it multiple times by clicking on the map, I guess x1 spawn would be a better option