when you look at BOM's from on line shops the fabrics are included - each month you receive a pattern and fabric kit for that month's block-so yes they can wind up being rather expensive- sometimes you just want to make it exactly like it it- the first BOM i fell in love with cost me almost $400 by the time i had all 12 kits-patterns and finishing kit-
i decided i like to pic out my own fabrics and save $$ but often in you want to do one with just the patterns (not the fabric kits) you will be charged $60-100 just for the patterns.
guess we have to pay for the convienience