Groupon.com has an interesting deal this week: for $39, you can get $79 worth of locksmith services at Lockbusters. The problem here is conceptual: people don’t buy locksmith services this way. Usually, there’s a lockout crisis and price is almost irrelevant (this offer isn’t valid for lockouts). So who the heck is going to buy locksmith services this way? It makes about as much sense as selling books by the pound.