Congratulations on a 'good' resolution to this issue. I'm also surprised that he came through with most of the money owed. Sounds like he's really struggling; tough times out there...
I had a similar situation when I purchased a pistol from a much loved forum that we are probably all familiar with. This guy delayed and delayed, avoided my calls and emails (of course, he was very responsive prior to me sending my PMO...), and then I got word that it should have been received at my FFL. He was trying to claim his FFL should have shipped it out to me, and maybe they 'lost' it. I tracked down his FFL (large retailer), told them what I was dealing with, and surprisingly got some pertinent details that helped me confirm that this guy was screwing with me.
Long story short, I left a voice mail message, and email, saying that I was concerned that since I did not receive the gun, I am going on the assumption that it has been stolen during shipment. I explained that stolen guns are a serious issue for a gun owner, and it would need to be investigated by law enforcement. I said that I was going to call the local PD, Postal Service, BATFE, etc. I also explained that I used to live in this guys hometown and am friends with the police chief there. Well, wouldn't you know, the guy's wife calls me the next day to say that she would be shipping out the gun; 2 days later I got it! BTW, I really am friends with the chief, and this guy did himself a favor by coming through with the gun...
As it turned out the gun was in very good condition, but not the "mint" condition as described

I really think some of these guys are just down and out, and will scam you if they can. All in all, it was a very shady situation, and I was happy to have not been taken for the dough... I am much more inclined to buy local, or doing some due diligence to make sure the person selling is reputable.