This is a really easy thing to do...you don't even have to leave a main city to do it.
ok first go to a major city (sw, IF org etc).
Then find a vendor that sells copper rods. get yourself a few copper rods.
Then you go to the auction house and auction them for about 4-5g each.
THAT IT. nothing else, then you just wait for them to sell.
Copper rods only cost 1.5 silver or so to buy off a vendor, but some people don't know that vendors sell them and just try to look at the auction house. when they see that theres none on auction, they ask around and THEN find out that the vendors sell them. This trick is targetting the people who look on the auction house before checking the vendors.
Note: Make sure you don't put too many otherwise they'll think that they're easy to get and try to find out how to get them, instead of spending a few gold. Maybe put on 2-4 at a time.
I don't do this anymore myself, so i decided to share it, but i used to sell about 6 per day, so thats an easy 30g each day with no effort...
i didn't want to rip people off THAT bad so i didnt set higher prices, but i went on another server once to test it, and i put ONE on auction for 18g and it sold...not sure if it will always sell that high though.
Don't think this can get you in any trouble either. no rule against it .