Where there are risks there are rewards. Sure, I could go "He just happens to be a 20th level wizard!!" *ZAP* But that's no fun. I want it to be useful, but there should be risks associated and most traps, etc are with dungeons.
Lets say that Grenelda the female Dwarven Smith does excellent business. Independent fighting men and women of all over Kalamar come to her shop and trade a gem or some ancient piece of artwork or maybe mundane coins for one or two of her swords. Lets say she does 500gp on average per day, she's getting old and mostly she just hires other skilled smiths to make the weapons, but her large inventory and strict quality control have kept up demand. On a good day she might sell several to a large mercenary group who made a large haul. At the end of they day she sends one of her trusted couriers and a guard (Eddie and Nunzio) to drop the gems off at the jewlers (in return for a writ), the art off at a collecters (for a writ), and the cash and writs at the money lenders.
Although not everyone with 5gp to pay a bar tab will have special protection, Grenelda would probably have some minor trinkets or what not to ward off thieves. She's selling swords so she encounters people who can cast spells on it in exchange for service. Say a Cleric of the Knight of the Gods (LG in Kalamar) wants to buy a MW greatsword but doesn't have cash. A couple glyphs of warding with hold person or acid spray in it might do the trick. It's reasonable to assume she has such protection being the nice person she is and open to bartering.
I don't want to make every pickpocket encounter memorable, sometimes there isn't anyone around, and sometimes the mark is surrounded by friends or in a crowd. But eventually they're going to run into special protections.
What protections would Grenelda have is basically the question. Nothing higher then 4th level spells. I like the animated construct or tiny undead though, that's fun.