I'm using muslin for a cathedral window quilt right now. The muslin was a lot cheaper than regular fabric and I had to get a lot .... 20 yards was what I was told. So I decided to buy a bolt of muslin but after shopping around I found that there are a lot of different qualities of muslin out there being sold. The box stores were cheap but poor quality so I ordered it from my LQS..... and I love it.... nice quality and I will have some for other projects. The LQS owner told me that there may be some flecks of cotton seed, etc in muslin that you won't get from regular fabric because it is less processed. That didn't bother me because I wanted the more country look. So look around to find exactly what you want.