Startup Idea: Real-Time In-Store Price Checking App

Startup idea to develop a smartphone app for retail industry that provides customers with real-time sales/coupons upon store entry via Bluetooth connection, and supports feature for random 'flash' sales throughout the store.

I work in retail and I wish there was a industry standard for in store price checking for sales/coupons. Something like a smartphone app that connect via bluetooth or something when you enter a store that provides the customer with real time sales/coupons. You could drive up sales by doing "flash" sales on random items throughout the store.