A very impressive calculation, a very interesting result. I recently embarked on a project in a similar area. My aim was to find a value for the runescape economy. Not a value in gold pieces but a value similar to that which real-world stock exchanges are measured. I created a spreadsheet which contained the items I considered to be important factors of the economy's value. e.g. Pure rune ess or yew logs. I used the forums to find the average amount of an item in a sale and it's average price (I took 10 results for both for every item. Yes it took ages and yes it was rather a sad thing to do). I then multiplied one figure by the other to find what I called the product value. i.e a number to represent the value of all of that item. I put every item into one of six groups, e.g. Runes and then gave these groups a value. When i added all the product values together I got a value for the RS economy and i could find which items made up what percentages of this. I repeated the process every week and by doing this could track changes in the values of both individual items and the whole economy. I would be very interested in anything you might have to say, i could probably either send the spreadsheet to you via e-mail or you could veiw it in google's new online spreadsheet software. Sorry if it appears that i'm trying to hijack your thread, that certainly wasn't my intention.