I get offers of 2-3k/hr for PLing quite often.  As a 59 druid with a Manastone. 
 
But camping something like Fungi Tunic or Hiero Cloak can, if your dice and the games dice are good, pay off much larger PP/hr rate. 
 
As a monk you can likely get into those cash groups (fungi / hiero) or you can PL people.  The rate you charge is largely based on your DPS / ability to continue PLing.  So a monk with Fungi + good weapons + good haste can charge much more than a monk without. 
 
At lower levels, honestly I wouldn't be too highly concerned with money until you get up into your 40s/50s where you can start farming things more reliably. 
 
Stuff like... Hooded Black Cloak in Mistmoore goes for a solid 3-4k. 
		
		
		
		
		
		
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