I get that idea that the economy of d&d was based on a gold rush style of inflation where goods were scarce and gold plentiful. Unfortunately these price lists have been used everywhere from border towns to magical fairy cities and items have been tacked on or price adjusted over the years until you have things like a length of chain costing more than the mule that's pulling it or dwarves buying plate armour off the rack.
In my old home brew campaign I tried to institute a couple different monetary systems, there was the focus empire where the silver coin was the base unit and there were Crowns, Royals and Imperials, the island nation to the south used long flat wafers of different sizes called Marks and the sprawling trader nations to the east used a paper money system. Since I'm neither a economist or a history expert I didn't have prices for items ready to use on demand so initially I tried using the AD&D ones or other supplements and just substituted silver for gold when making up prices. Even then it took time to reference them and then it took time to do the conversions between the different economies. This can be fun but mostly it isn't. As much as the default d&d coinage/price system sucks, I understand that most GM's (or their players) don't want to model a complex system like an economy. They want to bust up some shit. Aside from dropping unbalancing magic items and repricing expensive trinkets, when you are using modules from all sorts of places for encounters, it becomes a real drag to constantly tinker and correct the coinage on the fly.
So for Beacon I wanted to keep things close to the SRD while providing an easy out for the masochists that like to tinker*. I've included info from the SRD on equipment and coinage (especially the 10-1 ratios and coin weights of 1/3 oz or 50/lb). I've only tinkered with the price lists a little bit (because I can dammit).
Here's the easy out: There was an old empire now fallen and there is a lot of old coinage from back then still out in circulation. Especially in the dark caves and wild lands. That coinage is pretty durable stuff and people like it and use it a lot even though that use may or may not be looked favorably upon by the local authorities. I think there's a lot of potential in that idea. If you're in a society that has it's own monetary system and you come across a horde of 1/3 oz silver and gold pieces they might be fine using it in their markets or they may want you to exchange that coinage for theirs - they might want to tax it or even confiscate it. Or maybe there are no societies anymore.
Meanwhile there are a lot of good discussions on 'the blogs' about finance and campaign settings and these have useful information on everything from developing resource based economy to barter systems to historical price examples. I like the discussion about on The 25 Mile Hex about Manor Economics which fits in well with the traditional d&d 'end game' and gives some good ideas on how wealth gets carved out of those wilderness maps.
*I think that's a good design motto actually.