Eddie's Tutorial
http://www.quiltingboard.com/t-35742-1.htm
On page 8 he explains how to calculate yardage for the background. It's about 15 yards for a twin size.
For other sizes, I used his same size raw square (8.75 in) and use the quilt calculator
http://www.vrya.net/quilt/flash/QuiltCalc_Loader.html
I used the square, cut dimensions button, and size on one side to find the yardage for a double and it was about 28 yards. This site even tells you how many strips to cut.
83"X106"=21X27 (4" finished squares)= 567 squares
calculates to 27.75 yards. Round up to 28. That's a lot of material! But you don't need backing or batting so that helps with the cost.