I have a hard time anwsering your poll. For me it really depends on the animal which is being considered. I usually offer alittle wiggle room, but this does depend on the animal. There are certain BPs that I refuse to go below my listed price. Theres always a cutt off point tho where its just not worth the sale, I never go below what I recognize as my own "rock bottom" price. Offering payment plans is another way to get what you really want out of an animal too. if someone tries talking you down or offers you something close to what you are asking for it, bring up that you would except a couple payments. If you dont sell for a couple years, this is fine really.. price on breeders is much higher then babies.
Just my 2 cents.
EDIT* forgot to answer your question- I do not get offended at all by someone offering me something or asking if I can work on the price abit. I do get a little perturbed though when someone offers me half of what im asking for the animal lol. (sadly this happends)