Yes they were based on the daily specials @ Mo star. To calculate cost per sq inch just divide the sq inches into the price.
The cost will never figure exact on whole yardage because there is always going to be some waste. These figures are just to give an idea of how much is reasonable to pay for the pre cuts.
For me, .005 per sq inch, is a reasonable price to pay. So I would pay $20 for a layer cake or $5 for a charm pack.