Consumers who use comparison shopping engine TheFind’s Facebook shopping app now get e-mails whenever products they’ve Liked on any e-commerce site go on sale. The Universal Price Alerts are part of TheFind’s Glimpse social shopping app and are sent to whichever address users have associated with their Facebook account.

The price alerts are a way for e-commerce retailers to associate value and sales to the Like button, a TheFind spokesman says. “Retailers have spent a lot of time and investment on adding Like buttons, but they have not done a lot in terms of increasing the engagement level with it,” he says. “We saw this as an opportunity to take what we have in our index and deliver some pretty immediate value.”

He says a Glimpse app user that clicks the Like button on a product while browsing an e-commerce site is already expressing approval of that product, and an e-mail nudge when the price drops may compel her to go and buy it.

TheFind’s crawler that indexes products and prices across the web automatically picks up the price drop, meaning merchants don’t have to do anything to generate an alert. Approximately 140 million product pages feature the Facebook Like button, TheFind CEO Siva Kumar told attendees at the Internet Retailer Conference & Exhibition 2012 in Chicago in June. About 70% of top e-retailers incorporate the button, he said.