My one-and-only guitar since I bought it new in 1969 is a D-18, s/n 245998.

I had the neck reset a few years ago, which indeed made it easier to play. I don't know that it made the sound any better; the sound has always been very nice, and if it's better than ever now, that might be entirely due to its enhanced playability. (If it's easier to play, it has to be easier to play well and take greater advantage of its potential.)

I had an appraiser look it over in early 2006, and he pegged the value at about $2400-2500. It was an "informal" appraisal in the sense that it was free and undocumented. (He would have typed up and signed a letter attesting to that value if I paid his price, but since I wasn't selling, only curious, I was happy with the no-charge verbal evaluation.)

After reading the info on that "provide.net" site linked above, I suppose that the neck reset might have enhanced the value a bit. Or perhaps it made no difference ~ but it couldn't have hurt.

I might add that my guitar shows a fair amount of wear-and-tear, mostly on the spruce top, so that 24-2500 figure is NOT based upon "mint condition."

I would think that Seamus' friend should ask $2500 or even a litle more, and then be willing to come down a couple hundred. An even two thousand is probably too low, and would present the buyer with a real bargain.

PS: The CF Martin script logo on my headstock, originally gold-colored, is now black and almost invisible. I'm wondering if this is typical, if anyone has ever bothered to replace or refurbish theirs, etc.