When people use "negotiate", I think 99% of the time they mean price. It's really not a complicated concept
That may well be so but then it is because those people do not know the difference between bargaining (uni-variant/zero-sum) and negotiating (multi-variant/positive-sum).
When wanting to acquire a piano - a high price ticket object who most people want to keep for a life time - it is more wise to make oneself familiar with the technique of negotiation. It takes some time to learn and master it but it is worth it; that is why diplomats spend years mastering the negotiation technique and why many people should try making oneself familiar with to should they not wish to rum from one buyer remorce to another.
example source : bargaining is not negotiating
Although I will study the article when I have a chance, my first reaction is that very few people, including myself, most piano dealers and, even those who get the best deals on a piano they buy, know what some of the terms you mentioned in your reply mean.
I am sure it is something with which you are intrinsically familiar, even if you never bothered to put a "name" to it.
The idea is pretty simple. With a piano:
Bargaining: You are considering charging me "X". I want to pay a lesser value "Y". We work until we either find middle ground or we do not. In the end, what the seller loses (in price), the buyer gains (in savings). This is uni-variant, in that only one variable is considered. It is also zero-sum in that one person wins and the other loses.
Negotiating: You are selling piano "X". We bring into it tuning, regulation, repayment terms, loan/lease options, moving the piano, additional features (Dampp Chaser, etc), re-selling value, additional store credit, a bench, warranty terms, and any other number of variables you may be able to consider. This is multi-variant because there exists more than one variable. It is positive-sum because there is a chance that the buyer may "win" something that costs the seller "nothing", or may be willing to concede something of little costs that makes the seller's life easier.
Most commodity purchases do not have the option of being negotiated. Bargained, yes, but not negotiated. There typically are very few "win-win" variables. However, this poster is saying that if you can find any, you can (and should) change tactics from bargaining to negotiating.
One other key to negotiating: it is not time-bound. In other words, you can't have a one-time, short-lived experience with a seller and expect to be able to negotiate. Quite simply, you're not invested in each other's success long enough to truly equate potential gain. If you were leasing a car with an option to buy, and involving the company's loan department, now you have a longer-term situation in which negotiation can be utilized. But typical short-term and one-time commodity purchases with few selling options do not fall into this category.