Did the couple come back for the speakers?

This is one question that has nagged me since seeing the movie. Do you think Janees and her boyfriend/husband ever bought those speaker David showed them?

Here is my interpretation: David gives them his card. They call his cell phone while he is on his road trip; however, since David is basically in the middle of nowhere, he doesn't get reception. Therefore, he misses Janees and her husband's call.

Now, there are two outcomes to this. One is that the couple goes back to David's store and buys speakers from another salesman. The other is that they go to another store and buy speakers there. Both scenarios are plausible, but I guess we'll never know.

I hate movies that don't tie up loose ends.