That's interesting; it's never occurred to me to attempt to nitpick a price once it's been agreed upon. I've definitely found some objectionable issues with items once I've gotten in front of them - a leg vise that was described as "great condition" ended up being literally broken, and I didn't find out until I'd driven two hours to pick it up - but that's why I try to get into a ballpark price range before going to see something; if there's not going to be a chance of getting together on the price, there's not a lot of reason to waste the time and fuel.
And, I guess I've never seen the inquiries I've made as negotiation; I just ask someone if they have any room to move on the price, or I ask what their best price is. Most of the time, someone is either firm on the price, or they state something that's somewhat lower. If it's too high, I just say "Okay, understood; thank you!" and move on. Sometimes I get a text/email back asking for my side of the offer; most of the time I don't hear anything back. That's cool, either way...but in all cases, I've just tried to make the process as expedient as possible.
Regarding the Deckel... here's my objection: it's a better, nicer, rarer machine than I need. It's kind of like you said: you'd sell your dad's workbench to get one...but I wouldn't. To me, it's a nice machine that's slightly too big and that costs more than I want to put into a home shop mill at this point. I need something that's on the small-to-midsize end of the scale, and that's basic and solid, and that's not excessively collectible; beyond that, I'm really flexible on what I get. I like the 85XX or A1S size, but I could go any direction beyond that...and I think that's where I differ from the Husky seller: it's very important and valuable to him, but to me - now - it's a tool that's the right size, but no more.
On that topic: if anyone has further suggestions on alternate options, I'd still like to hear them. I've already altered my opinions on lathes after getting lots of input on that front...so I'm willing to do that with mills as well.