Try to find more out of the way shopkeepers that might see less traffic. For instance, all else being equal, the armorer in Galadon will probably be running low on coin before the armorer in Seantryn. The more remote the shopkeeper, the more likely they will still have coins, so keep an eye out for random shopkeepers that aren't in towns. Also, when you get to the mid-ranks, you may be able to find shopkeepers that you can kill. When they repop, they'll have more gold. Viola.

Also, there are a few lowbie quests around that give you coins for killing low level mobs. The money's not great, but it's something.

One other idea is finding/looting decent gear and selling it to high level characters who have lots of gold. 10 gold at hero is worth waaaaay less than 10 gold at level 15.