But bartering could be an interesting proposition. I think most barter systems are one step away from using a currency; if you're trading chickens for swords it will eventually be easier to standardize on the value of things in chickens or swords. But standardizing implies authority and enforcement and some places might be far from civilization.
So bartering could give a nice flavor of either being in a post apocalyptic world where there is no government and what is dredged from the wreckage of the former world is always unexpected and hard to put values on, or the savage frontier where merchant houses and authorities are far from the trading post.
Bartering could just be handled by roleplaying out each encounter with a merchant. I usually do just this, rolling reaction rolls to determine if they have requested items or not, and how much they will ask for them.
But that doesn't help the busy DM much and it doesn't give the players a sense of a teeming market place. So, can we come up with a mini-game to help?
After thinking about it, I think a dice drop chart of the most common gear would work. Take a sheet of paper and split it up into sections for each piece of gear. Cheaper, more common items can have bigger sections.
|Orange will give sacks for torches or spikes, sounds like a crappy deal. How do you like my ghetto office dice?|
Let the players look at the market. It should sometimes be possible to identify strings of possible trades: this guy has an excess of rope, this guy over here needs it, etc. Players with exceptional Charisma can shift the numbers on one of the dice for each merchant up or down one. You can roleplay out the rest.