What qualifies a "low baller"

My opinion of this is simple, say you have an AudioEverything VT1000 amp, and if you look on Audiogon, Audioweb and Audioshopper and there are 10 others for sale there all between $500-$750. You have priced yours at $450. When someone offers you $250, that in my opinion is a low ball offer.

Short of developing a crack habit, I dont see myself ever being interested in selling something 50-75% below the fair market.

No set definitions. If the seller indicates that they are firm on the price, I believe that the only negotiation area is shipping. If nothing is said about being firm on the price, but there is no "or best offer" clause next to the price, I would say that anything below 90% of the asking price is low balling. If there is an obo clause (then the seller can't be firm), I believe low balling is an offer that is less than 80% of the "blue book" or market value. That could go to two-thirds if the item has been for sale for at least three months and the seller invites best offers (obo) in the listing. Gets complicated, doesn't it?

Speaking solely for myself, I always try to price items fairly -- to me, and to the prospective buyer. I deliberately do not inflate my asking price simply to leave a lot of "haggle room". Hence, I'd define a low-ball offer as one that is more than 15% below the price that I have asked. I usually succeed in selling most items for my asking price, or maybe 10% less.

I have had only one recent instance of a real "low-ball" offer. I was selling some Kimber 8TC cable at slightly less than half of the MSRP, and got an offer from a guy to buy the cable for 25% of MSRP (about half of what I was asking). I simply sent him a "thanks for inquiring" note, commenting that my ad stated the price as "firm".