You would think that finding information on medieval trade and economics would be easier. This is what I ended up finding:
One $basic_unit_of_currency, which was the wage for a day of skilled labor, could buy:
1 loaf of bread, or
1 bottle of cheap wine, or
1 evening with a prostitute
...which makes me think that the Evening With a Prostitute is a great idea for a unit of currency, just because of the conversations which would arise:
"Father Yusef went to market and spent three evenings with a prostitute. He came home with a goat."
"Hey! How many evenings with a prostitute can I get for this horse?"
...you get the idea.
Actually, the standard units of currency in the Byzantine empire of the time was the gold solidus, the silver miliaresion, and the bronze nummi. I am having difficulty finding their relative values, and any real-world goods of the time to determine the purchasing power of those coins. Since a significant portion of the plot of my game is to earn a specific amount of money to pay back a debt, this is kind of important.
I have ordered Macromedia Flash Professional 8 Game Development, which should arrive Wednesday. I looked through it at the local bookstore and found some significant tutorials on the Flash 8 bitmapData class, which will go a long way toward optimizing the graphic output of this game so it doesn't eat up 90% or more of the processor during the more graphically intense moments. And the author, Glen Rhodes, wields a staggering amount of mojo in the field of Flash game development.
More as time progresses.