So someone's come in with an offer - great! The bad news is you feel it is insultingly low! Don't get personal. Remember it's a start point and it's your big opportunity to open negotiations. Of course buyers will want to try to buy your house fo the lowest price possible! They know they can always go up, but they can't go down. It's not personal as far as they are concerned, it's a business transaction.
So you react by coming back with a counter offer. Typically, a buyer will come back with a second offfer, which is closer to the real price they have in mind that they are willing to pay.
Don't throw away the sale over something silly
If there's a sticking point and a buyer wants a item thrown in as part of the deal, it's crazy to throw away the deal by refusing to budge. You have to keep a sense of proportion. If you are selling a £300,000 house and they want you to throw in the stand alone American fridge, is it really worth losing the sale over it? Just think carefully before over-reacting.
You will be able to source another one - but you may not be able to find another buyer at that price - think of it that way. So unless it's a family item of great sentimental value (in which case tactfully explain this to your prospective buyer) then just think about where you will be if this whole deal falls through and the impact it can have on you and your family being able to get on with your new life. There are bigger issues at stake.
One top tip is to replace items that are non negotiable with something else before you put the house on the market, then it can't become a bone of contention.