I can understand the attachment from both sides. You've put your time, money, and effort into making it yours, and you are not obligated to make anyone else's dreams come true. You can be sure that if you or he were to find another Demon to replace it, you will need to make repairs or changes to that one in order for it to be comparable to the one that you already have.
Several years ago I found a car that I had bought new off the showroom floor when I was 21. I had every intention to keep that car forever, but in reality was forced to sell it after only 6 months due to the loss of my job, and a recession, during which I could not find another job. I was both very excited and surprised that I had found it, and it was for sale, and still in very good condition some 25 years later. I spoke with the seller on the phone at length, he sent me dozens of pictures, confirming the VIN and condition, but we couldn't agree on the price.
Part of the reason why I was not willing to pay his asking price was that I had found a nearly identical one for considerably less money, and it had a freshly rebuilt motor, and new wheels and tires.
Long story short, even though I would have liked to be able to get the one that I had bought new back, in the end I was far better off putting the emotions aside and buying the best value for the $$.
Sorry for the rambling post.