This is an old list well known to people who do world building, but it's still a really good and helpful one that deserves a wider audience.
1 shilling corresponds to 1 silver piece in D&D terms.
1 pound corresponds to 1 gold piece in D&D terms.
1 penny corresponds to 1 copper piece in D&D terms.
There is a small inflationary trend going on over the period in question, but nothing like the rate of modern inflation. However, you should keep in mind that an average laborers wage roughly doubled between 1200 and 1500 when making comparisons like that between the carpenter and the armorer.
It's also worth noting that for servants like Squires or 'Kitchen Servants', the total wages include room and board (basically, your share of the leftovers, often spelled out in the order of who got the first dibs, and a warm place by the fire) and the job was considered to be more of an 'unpaid internship' sort of position. The cost of room and board isn't included in the 'wage' listed above.
Gygax's prices - and thus the prices D&D have historically used - tend to be rather accurate in the case of non-adventuring supplies, commodities and labor, and radically inflated in the case of adventuring supplies and anything else that PC's would want to buy. Gygax himself outlined the justification for this in the 1e AD&D player's handbook, noting that the prices for things like swords, tools, and the like assumed that the players were beginning play in an area similar to the Klondike gold rush. Somehow this fundamental fact got lost over the years, and people have tried to make a functional pricing system based of the 1e AD&D prices without taking into account the fiction behind them.
One of the most important historical corrections you can make to standard D&D economics is realize that to correct "PC pricing" to the historical pricing, it's usually just necessary to divide by 20, that is - convert gold pieces to silver pieces. Most D&D prices are pretty decent if you assume the thing is priced in silver rather than gold. Gold was vastly more valuable than typical D&D price lists tend to make it. Note for example, the income of the Crown for an entire year was roughly 30,000 gold pieces - less than a PC might value a single magical item. Once you get PC's and the rest of the world on the same standard, you can start thinking about a more functional economy.
If I can make one other suggestion, manufacturing and powered transportation have over the years made the cost of goods relative to income lower. But the cost of handmade goods over time, when adjusted for inflation (and if need be, purchasing power parity) is in my experience relatively constant. Any offset in lower price owing to the decreased cost of raw materials tends to be offset by the increased expected standards of living. So wherever tables like the above don't provide direct insight, a reasonable approximation can be made by looking up the price of a hand made good (a hand tailored suit, or hand crafted furniture, for example), and then making the following (rough) conversion:
$1000 = 1 gold piece
$50 = 1 silver piece
$5 = 1 copper piece
That has worked for me really well in understanding what a price in D&D terms means.
