All you need is a low level weapon, anything under lvl 20 I'd say will be fine. Make your way to the Weyward Tether Proving Grounds and find a Thieving Jabber carrying a wooden barrel and carefully kill the Jabber and it will drop the barrel. Clear out the rest of the area, then come back to the barrel and start shooting the barrel with your low level weapon for unlimited money. Best to use a cash boosting artifact and be playing on Mayhem 10. Hope this helped, please leave any questions in the comments and I'll get back to you! Stay safe out there Cheers.