I've had the same thing happen with other stores too .... specifically .... Wall Mart. One year we were looking for new patio furniture. The flier had exactly what we wanted and had been looking for, for a long time. We took off to our closest Wall Mart and sure enough, there it was, on display! We thought! Yahoo!
Well, we couldn't find any boxes or sets on any of the shelves at all. We searched and search and then started calling other Wall Marts to see if they had any. None. We then asked for management and started raising a fuss.
He said "corporate" sent only the one set of furniture, and it was to be used as a display, and "No" it could not be ordered on line! What?????? Well, more fussing and by now, we're getting pretty vocal, screaming "FRAUD!" and in order to quiet us down, he ended up selling us the open box floor model. We took it and actually got a lower price because one chair had a slight defect and now they had no display at all with no prospect of ever getting another one. We still have it, it's on our front porch as I'm writing this. A simple fix on the messed up chair and it's still doing very well.
So, yea .... it can happen. When it does, you just gotta go with the flow and hope you get lucky! (but my flow was pretty vocal).