Using a layer cake, you would need to cut off 1 1/8 inch strips to come up with your 8 7/8" squares...those strips will be wasted unless you are willing to make something with strips that skinny. I thought people used precuts to save cutting time...no time saved and possibly wasted fabric. Doesn't seem wise since layer cakes are more expensive to begin with. That's one reason I don't buy any precuts except FQ's.
The average layer cake bundle is $40 and contains about 40 squares. One yard of fabric yields 12 10" squares (plus 2 strips of fabric). So, a layer cake is equal to about 3 1/3 yards of fabric. That's just over $12/yard for layer cakes.