Shopping, sales and deals, Oh My.

Consider creating business profiles. As opposed to check-ins, vendors could post information like items on sale and current deals. Normal users should be able to follow specific vendors or just tags, like jeans or doughnuts (generic) or specific tags like Head MicroGelTM Prestige Pro. Users then should be allowed to choose how they want to be made aware of deals. They might choose to be notified about their favorite vendors/items-by-name when items are posted, regardless the proximity. For generic tags, they might wish to be notified if they are close to a tag of interest.

You could also use Google Maps and allow them to see deals and sales along a specific route. This of course would be a beast of help when planning to shop. Which course of travel saves me the most money? A feature that allows users to post items at ridiculously low prices might be interesting too.

Another tack might be shopping events day, like a saturday. Based on tags, which implies, 'Be on the lookout for this item at really low prices!!!'. The user who post the item that other BK users ended up purchasing the most and so saved the most other BK users the most money gets something special. I'd speak to the vendors about supporting this somehow.

Think about it. If you do it, movie tickets and groups around shopping interest might be a good way to go too.