I might be beating a dead horse but your math is wrong. If there is a $.025 difference then that is 2.5 cents not .25 cents like you were thinking it was.
Figuring you use every square inch on the roll...
651- 150 x 12= 1800 x 24= 43,200.....79.99 / 43,200= .001851 per sq inch
751- 150 x...