Is a offer of -20 percent on an OBO ad insulting?

Again, thanks for all the interesting discussion!
BTW, my offer was worded "I'm interested in your amp, would you consider $XXXX and splitting the shipping?"
I don't have access to the Blue Book prices but his asking price, compared to the new price, did seem low. I know from personal experience, if I'm selling something that I've purchased used, I'm willing and able to sell at a much lower price, of course I didn't know if he was the first or third owner. Most everyone expects and has tolerable amount of loss when reselling an item. It's only through friendly negotiation that a good deal for both buyer and seller may be struck.
FYI, I've just sold a Cinepro 3K6SE ($7000+) for $2499 and I paid the 2nd Day Air, PayPal fees, & auction fees. I guess I'm just easy!
Still looking, Jim

I had a similar situation recently - a pair of speakers was listed for about 25% off retail. I thought that was a little high all things considered - they weren't just a week old or anything - so I offered something around 33% off retail and got a somewhat indignant and insulted no... (but he didn't do antyhing weird, like block audiogon!) I never got around to replying because someone else posted the same set for around 50% off retail and I grabbed them within minutes...

Maybe the seller has his thoughts that the asking price is more than fair, and that the buyer should be educated to know. What the seller fails to take into account is that there are always lots of Krells for sale. So its buyers choice. Seller is a tad upset that he's not getting enough response on his ad, not moving fast enough. If the seller tried to meet him half-way, 10%(take the hit and move on), it would have been a fair deal for both. The seller could easily have ignored his email.

Tweekerman, brings up good point. If a piece is put up for sale with "o b o" then a negotiable sale is implied.

In any given instance - yes or no.

Assuming the price is listed out fairly, an offer of 80% is insulting.

Lets take a Nordost Quattro Fil cable of 1 meter - they usually sell for between $750 and $800 on Audiogon. Assume a listing price of $750, and an offer of $600 - that is ridiculous, and not worth a reply.

Of course, the seller takes a risk of never selling the product too!