Challenge: Implement price discrimination in a setting where all prices are published on the shelf under the product without knowledge of who is viewing the price.
Possibility: Develop a "loyalty" program where customers provide a member id like a phone number at checkout. Anonymous shoppers get the worst pricing. Everybody else voluntarily signs up for price discrimination disguised as rewards.
Also the low-tech version: farmer's markets, bakeries, anything with perishables they sell daily will often give steep discounts or freebies if you show up close to closing, rewarding those that are in-the-know or are willing to modify their schedule to save some cash.