need help with pricing

[Poor Peter]

Howdy All,
I know this has nothing dead-related about it, but I figured with all the intelligent people on here someone may be able to help me.
I have a 1991 Martin Shenendoah S00-28H that one of my band mates wants to buy from me. My problem is, as far as I can tell, this is a relatively rare instrument. I found lots of info, and prices regarding the Shenendoah line, but not for this model. I know what it is worth to me, but I don't want to take advantage of this guy, nor do I want to give it away for less than it's worth. I am hoping someone can steer me in the right direction as far as getting an assessment on this guitar. All of my google searches have come up empty.

Thanks,

Po' Pete