I do love Jamis mountain bikes, in fact my current mountain bike is an '09 Jamis Dragon 29 (Reynolds 853). Confession: that's what attracted me to this thread.
I ride a 17" frame and I'm 5'7.5," for what it's worth. I've done a lot of mountain biking, and this Jamis 29er I'm currently riding is my favorite mountain bike ever.
I own a bike shop, and we are a Jamis dealer. My take on older, used mountain bikes (let's say 10 years old or older) is that it really doesn't matter much how nice they were when they were new, the bottom line is that they are a 10 year old or older mountain bike, and they have, to use an accountant's term, depreciated out. There are exceptions, of course, in the rare case of a collectible bike, but for something like a '98 Jamis Dragon, nice as it was when new, it's just an old mountain bike now.
When we get old, used, decent mountain bikes like this in, we can usually sell them pretty quickly for $150-225, depending on condition. The reality is that the 13" frame size would probably be a big hindrance unless we just happen to get lucky. But we'd be wasting our breath trying to convince someone it's worth more because it's a Reynolds 853 frame instead of some lower grade of chromoly; the typical customer for that bike simply doesn't know the difference and doesn't care.
Not trying to be a downer, just calling it like I see it.