I do it like this...first I do homework, research prices,(ebay SOLD listings can give you a good idea of price range for different conditions) average conditon for age,what are common defects,or upgrades, options for the model etc to get a good idea of what I should be paying for a particular instrument... I offer a bit less than what Im willing to pay giving me room to improve my offer, while giving them room to lower their price. If I think its a fair price...I just pay it if I can afford it, or move on and save more money if I cant.
If I think they are way over pricing it, Ill contact and ask if something "special" has been done to it as I usually see them going for"X" amount, with possibly a link to a completed EBay sale or two as reference. Many times these sellers are uninformed and after seeing reality they come back with a different , more reasonabl price. opening the door for a counter offer and the dickering begins
I always point out and mention and defects or damage and discount my offer to reflect them.
and then I sometimes am in a position where money is tight and I just tell them...look, I think your price is fair..but all I have that I can spend on this is "X" amount and let them decide..I often get a call back in a few days if no one els shows interest.
Hope this helps...Its worked for me..
74 Guild f112.....$400 pawnshop
1 year old Gibson Les Paul.... car I bought for $50 and $50 cash
MIJ Squier A series (85).....$84 Pawnshop
96 Guild DCE-1 ....$250 CList (needs Binding reglued)
Epiphone Masterbilt DR500M HR ...$147 flea market guitar stall
Squier VM Tele Custom.....$25 needed 1 pickup
these are just some of the deals Ive gotten over the years on guitars I still have. Most of these were situations where I didnt have much cash and offered what I had as opposed to what they were asking while doing all the other bits about condition, etc...all were accepted obviously lol
mostly you have to "feel" your way through it with each person, as we are all different.
I try hard not to be insulting, and If do end up giving a low Offer, I apoligize in advance...I hate to be a lowballer, but all I have is "X" to offer right now...sometimes people just want to move something along and will meety you more than halfway...
hell Im doing it right now as a seller...meeting someone more than half way that is..
truth is I sometimes offer more than they want if I think they are ripping themselves off..
for instance, a "friend of a friend" that I know a bit has offered me a MIM Strat and a smaller Peavey tweed amp for $100..told him I wouldnt feel right if I didnt give him AT LEAST $150...and truth is Im thinking of going up to $200....He bought the stuff new, its been sitting in the corner with rusty strings ever since..he's played it maybe 4 times according to him. Hwe loves his acoustic and never plays electric. Its perfect.amp too.
not my best bargaining techinique....lol
Good Luck and I hope this helps