We held out longer than most before switching from film cameras to digital. While we were still using film, I noticed in the local market that the larger packs of film came to more per "shot" than the smaller ones. I found some cheese today, with the same product available in 8 ounces for $2.12 or 12 ounces for $4.29.

When I've heard the expression "cheap at half the price", it's always been as a plainly sarcastic way of cxpressing an opinion that the item is grossly overpriced.