Do you even ever bother to make an offer to someone who is asking 50% more then "fair" for a gun you want to buy ?

For example I was looking at a Glock 23 , I see most used ones in the 400-450 range , some guy is asking $600 on one locally, would you even bother offering $400 ?

Only if its worth it and you have the money to back it up.

heck yeah i would,,i tell em like this , im not rich and if i can get it cheaper i will..if he gets mad, i wouldnt sweat it,,all he has to do is decline..also what he said ^^^. dont low ball sumone and then they call your bluff and then you tell em you dont have the money or your jus shoppin, if sumone low balls me, i say, lets see the green, if not , then ya tell em to take a flying leap.

7 years ago I found an unfired H&K USP40c in a "used gun" case.  It had a tag of $650 on it.  I asked if the shop would take $500 cash right now.....
They called the owner, turns out it was a consignment, and he said yes.

Didn't hurt to ask....

$400 for the gun would fall in the range of a fair price, if used.  However you didn't say if that included hicaps ($50-80 ea.) or some accessories like a lasersight.

New Glock 23's sell for $499 (or lower) out here in CA at certain places so the $600 price is out of line if it's just the gun and 2 10rd mags. edit: I'm looking at an ad at a local gunstore for a Glock 19 for $489.

Engage the guy in conversation find out why he is asking what you think is a high price. Maybe he's had some custom work done on the gun. Make an offer. The worst he can say is no. Never ever criticize another man's gun. Be tactful. Even if the guy is totally full of shit, there is no point telling him so. Just tell him you wish you could afford to pay that much, compliment him on a fine firearm and walk away. He may have a change of heart later and remember you.

Sukebe is right about not critisizing the seller's gun.  I usually ask to look at the gun.  

I say something like, "This is a nice gun.  I have been wanting to find one for around $400.  Would you take $400 for this one."

If he says, "No way."

I say, "Okay.  Thanks for showing it to me.  I hope you find a buyer."

Why not be pleasant?  You have nothing to lose.  I've sure picked up a bunch of bargains by doing this.

Recently, I went in a gun shop.  They had a consignment pistol, a 1911 Springfield with a bunch of after market gegaws on it.  It looked like someone had about $1,000 in it.  It was priced at $525 plus tax which put it at $568, a bargain.

I told the guy behind the counter, "I would be willing to pay $500 out-the-door."  He said, "No way.  No discount and you have to pay the tax."

I said, "Thanks anyway", smiled and left.

Went back the next day and there was a different guy.  I told him the same thing.  He said, "I'll talk to the boss."  Came back and said, "I can go $475 plus tax."  So, I walked out with the pistol for $514.

If you don't bargain, you never will get a deal.

You said it straight.
Some people say Ill give you $400 . Then they get an A.O-K and then back out. You offer. you better have the green.
GG

YOU BET!  Look it is a binary solution set - yes or no.  One way you get what you want at the price you can afford.  The other way allows you to stop wasting time on this one and go find another.

SRM