Did you know that a king sized flat sheet gives you 11,016 square inches of fabric to work with? Thats the yardage equivalent of just under 7 yards of cotton by the yard (based off of 44" wide fabric)
Thrift stores are a gold mine of vintage print sheets that mimic the bright happy floral motifs of the 50's and 60's. King sized sheets can usually be had for around 5 dollars. You can get a nice full skirted dress out of one $5 sheet instead of 5 yards of cotton from the store. If you're lucky you can catch a good sale and spend $6 a yard. $5 vs $30? I'll keep hunting for sheets!
Image courtesy of chaletgirl