The extra paper/ink etc would be offset by the lower postage prices though wouldn`t it ?

I try to charge the correct postage, and not make money on it, but this morning I got caught with something I thought was going to be $8.95 postage ending up being $14.95 postage. Item only sold for $8.95, so lost money on that. C & S Flat Rate postage wouldn`t have saved me that extra postage cost cause it was interstate