neither player is the designated "offer-maker"; either player may begin by making an offer

This is often not the case. It's common that the table will have a price tag on it which the buyer can take or leave. The salesperson isn't authorized to hear a counter-offer. Becoming the offer-maker in all your transactions and using that leverage to buy and sell at a profit without value-add is a viable business model.

I realize this wasn't what your post was about, but the role of offer-makers and offer-takers in commerce is important and often overlooked.