The case I'm thinking of is informal. The pharmacist keeps a blister pack of pills behind the counter and will tear off as many as you want and sell them indivi

The case I'm thinking of is informal. The pharmacist keeps a blister pack of pills behind the counter and will tear off as many as you want and sell them individually. The unit price is probably higher, but not exorbitant. It's probably against the rules, but the pharmacist deals with poor people all the time, and he isn't trying to gouge them. And I think it's the perfect example. What good is a better unit price if you can't afford to buy in bulk anyway? If you're poor and you have a headache it's better to pay 25¢ for two aspirin than $10 for 100. Part of being poor is steeply discounting the future. The other 98 aspirin might take care of headaches for the next two years, but a lot can go wrong in in that time, and that $9.75 is money you need today.