When you calculate the time it takes to re-create a pattern is it more than the cost of a pattern? Lori is right too, if we guesstimate what we need in fabric we over buy..or worse under buy then not be able match the fabric later!
If I don't buy a pattern I try to use a fabric calculator or free design sites to get my estimates.
http://search.quiltshops.com/calculator/calculator.htm
http://mywebquilter.com/index.aspx