He has some knowledge, a bank roll and has no problem waiting for lil fish to swim by and pay top dollar for a Bass that he took the nice case from and put with the other Bass that is as beat up as its OHSC.
Sadly, this is probably what happened. The nice instrument probably came with the nice case and vice versa, and he switched them to try to bolster his ability to overprice the lesser one.
I also agree on being willing to walk away (and sometimes actually doing it) as being one of your greatest assets as a buyer.
I once went to look at a drum set. I don't "play" drums, but I'm ok and like to mess around at least, and was hoping to get better and use them for recording (with either myself or someone else playing them). Anyway, the guy who owned them was this young guy (maybe 18-20 or so), that either lived with his parents or maybe just some other people in a SFH. He was asking $450 I think, which overall was a pretty decent deal to begin with, but maybe not amazing. When I get there, the drums themselves are mostly in really nice shape, but the snare head and 1 or 2 of the tom heads were beat to hell (easy to fix, but it does mean more money), there was no snare stand, and the cymbals were clearly cheap ones from a started set and one of them was missing, along with a stand for it.
Anyway, he came down to maybe $425 or something because of the snare stand, but I didn't really think that was good enough. I offered him $350 and that was really all I was willing to pay at that time. I kind of had a budget in mind for the project and getting another cymbal and stand, getting a snare stand, and getting the new heads I would need, and oh yeah, it didn't come with a kick pedal either. I was basically just getting a shell pack. But he was like "no, I don't need the money, I just can't really play them here in the house, I want $425". So I said "thanks for your time", and I left.
That was on a sunday. On thursday, he texted me that he would do $350 if I was still interested. So I went and picked them up a few days later for what I originally offered. I never did really complete them with nice cymbals and whatnot, but I was given a kick pedal and also a snare stand, and I bought 2 or 3 heads right away to get them going, but then they ended up for a long time being the practice kit for one of my bands, and so the drummer was putting new heads on them every so often (I think about twice total over several years). I eventually sold them a little over a year ago for $550, mainly because I didn't have the space for them any more. I had had them for about 8 years at that point. So even with inflation, I still made maybe $100. If I had paid his asking price in the moment, I maybe would have broken even. Not a lot of money, but if those kinds of habits are repeated habitually one way or the other, it adds up.
As a seller, I've kind of had the opposite experience. I list things for what I feel is a fair price, with a little wiggle room, always expecting people to at least try to haggle, and as a buyer I almost always try to haggle, unless the thing is already priced crazy low and I would feel bad trying to get it for less. And for instance with craigslist at least, 9 times out of 10, the first person that looks at something is the one who buys it (sometimes with haggling, sometimes not). Maybe it's because they're the first ones who are serious, as opposed to the all "Would you take 12% of your asking price tfrom an online stranger?" tire kickers.