Those instant level ups can be expensive.
My suggestion is a "quest reset stone" or something which is much cheaper and resets all quests including major quest lines. Reset stone could be all quest, just Morrok/Tony quest, zone quest, land quest (eg Candara, Zandorya etc) or different zones.
I don't really know the effects of this.
Might be better for newer people who want to quest and level up but run out of quests.
Might not be many who actually want to buy it tho, no idea