how do I know if they have an advertised item. The store is 20 miles away and I have found that items often do not come in?

You can't call directly to them low overhead so unfortunately you'll have to go there or find a friend who's going that way and ask them to stop in for a moment. Most sale stuff goes very quickly. Sorry you're so far away. The best to you.

Call ahead

That is my suggestion also, some time the employees are busy

I suggest calling the store.