you can clean around 8k herbs an hour i find.
depending on what herb, you can possibly max 80k exp per hour.
this is just from my personal experiences
hope this helps.
thought i had seen that bank picture before.
low and behold
http://forums.zybez.net/topic/1147390-lvl-138-like-a-boss-2250-total/
from the march 22nd entry.