Well how about adding IO eternal harp to blood marks vendor ?
Those harps just basic it's nothing OP about it.It will help lower gap between new bards and elite bards.
You can even do custom NPC merchants that selling instance gear skins like IS,BT,DP or craft one like lv 55 with blood marks or ancient coins.
Or maybe buying consumable foods with AP ?
Maybe even selling primal spirit skins with kahrun symbol that would make high level players helping low levels farming kahrun gears which needs for class like cleric/chanter.
I don't think you can make much money from primal skins from shop anyway I don't see anyone even using them.