What to do with very low offer on an item for sale

I would always thank them for making an offer but you are declining it.  No reason to be insulted.  I have set up (3) systems buying used.  I tend to "lowball" - but never 25% of asking.  Sometimes the seller and I reach a deal right away.  Other times they decline then approach me in 30 or 60 days if the unit hasn't sold.  Usually I have bought a different piece by then and have had to decline.  And sometimes they get pissy with me.  There are multiple reasons to low ball.  The most common for me is I am ready to buy let's say a speaker for $ Xk but I see a Wilson Benesch that looks good too. That guy wants $ X+Yk for the WB.  I may throw him an offer for $ X to see if he wants to sell it.  Sometimes they make the decision difficult and other times not so much.  Another reason someone alluded to is budget constraints.  Another is just the risk associated with buying a piece sight unseen and/or unheard.  I dont live in a major metro area so i cannot always audition the speaker and need to be able to get my money out of it if i dont like it.  The key is to take the high road.   You can also use the word Firm in your ad.  Good luck !

"How would a car salesman respond if I offered $20k on an $80k car?” - good question! lemons sold to squeeze a juice from buyers! LOL 

my answer is “depends”! -is the car a brand new one, no previous owners/mileage driven? -is the car of well established brand, reliable model, with predictable life-time, 200k+ /mileage before “problems” start? -assuming it’s second/third hand one, what is the rest of life/milage estimate, for buyer? 

If recently listed it is either a bottom fisher, just someone who wants to play or someone using this tactic to get you to budge lower than you otherwise might.   For a new listing that is priced fairly, if it were me I wouldn’t entertain any counter offers but only state No Thanks and remind them its a fresh listing I will stick to.  Don;t even suggest a better price.

I sold my Hegel which was Mint but I used it several years.  I researched the price ranges and started with above average but not the highest.  A competitor listing had the same amp listed and as he came down, I came down. 

The listings sat for a time which doesn’t mean anything other than an interested buyer isn’t available at that time.   I finally agreed to a price that one consider absolute low especially for a mint but used amp and for a price the buyer came over to buy directly.   Doesn’t get any cleaner than that I suppose.

One year later, the same amp just sold for $400 more than I sold mine for but that’s how this is played.  Someone was willing to pay a higher price, presuming it actually went for that price.  That I would consider the absolute high at this point.

Outside of pricing something too high and/or someone asking for 10 to 15% off, much outside of that range isn’t viable to consider.  Some things, say inexpensive gear I get the price I ask, if its older and sits awhile, I may consider a discount that is acceptable to both parties.   

If you offer 10%, he/she may reject it but know how much you’ll drop today.   If they wait and it still hasn’t sold, they could come back and ask for a bigger discount.  

I would probably restate what makes this speaker a fair price, ask what kind of equipment they are using and perhaps to speak by phone before talking any price adjustments.  

I've been low-balled before and never entertain offering them a better price.  And I remember their handle.  

I have often observed that some think thier stuff has high value and your stuff has low value. Just like the old adage about thier manure not being malodorous. More to the point you get a percentage of supercilious sorts on this internet thing. Seller emptor too. 

I either don't reply or reply with a price *above* my asking price.   I take time to fully research the market for what I sell.  I write a very detailed description and include a lot of very clear, well lit, high resolution pictures.  I set my asking prices slightly above recent average sales, but not at the extreme high end.  Some may say my prices are aggressive, but I have received my asking price or very close 95% of the time.   I recently listed an item in several online sites and received a low offer from one person.  I replied with a higher price and did not receive a reply.   The items sold at my asking price 2 weeks later.  A week after the sale, the low baller sent another inquiry reiterating their original offer.  I replied that the item was sold for full price.  Person replied and seemed to be very surprised that my item sold.