That seems unbelievably low to me as these don't appear for sale around here that often. I just sold a used and refinished 908 for $400 and a used 908S for $450 and both the me and the buyer thought that was very reasonable for these sturdy and dependable pistols. If you could find one for $300 I would think that was a serious bargain. I'd sure buy it.
I just sold a 98% 908 for $320.00 One gun dealer offer me $240.00 for it, which was ridiculous. He said it was an "undesirable" gun. Which means he probably knew he could sell it the next day!
Sometimes even though it says "no reserve" the seller may have buddies who will bid on it to jack up the price if he has a set price that he will let it go at. My gut tells me that most folks, including me, have never heard of a SW 6904. Thats why you may win it!!
Was the high bidder on GB back in November for a 908 @ 95%. Paid $214.00 plus shipping. Have really enjoyed this one but then I really like all 3 of the S&W auto I have.