Sure, people get attached to inanimate object like guns and cars all the time. So if the seller still balks, tell him to call you when he's ready to sell.
I once traded a Ruger M77 to a friend's father for a BAR (mainly because the Ruger shot really well and the BAR did not). A week later, he wanted his BAR back, said I had taken advantage of him. I said OK, let's just go back to the start, you give me my Ruger and I'll give you back the BAR. Oh, no, he was in love with the Ruger, but he would trade me a 308 HK for the BAR (I assumed it was a HK91). I thought it was a little weird because an HK91 was worth more, but what the heck, sure. Turns out the HK was a HK 770 semiauto sporting rifle, not an HK91 like I expected. When I mentioned this, he threw in $100 in boot, so I shrugged my shoulders and said OK (the HK was easily worth $1,000 at the time, as opposed to about $500 for the BAR). He was just attached to the BAR, I guess.