I found a way to never worry about money again. Learn how to pick
locks. You can go to lots of different shops (Shrouded hills for 
example) pick the locks (a set of lockpicks/auto skeleton key make
a big difference) to their back rooms and then the one on the chest/
barrel/crate. All of the items they have for sale are inside those 
chests. Find the stuff that sells for a big price and sell their 
own stuff back to them until they're broke. They get a new supply
of money every day. Save the game next to the door before you pick
it in case the lock jams or they get pissed and attack. This trick
won't work in all shops but it works in enough of them.