What ultimately determines the value of a guitar?

[Doctor Jeff]

The OP's question is like - why does a girl like him and not you?
Is it his hair?
His build? His looks? His car?
Ultimately, it's just that she likes him and not you.

Some girls have no taste though.

[mr quick]

I work at a music store, and I will often say (jokingly, but there is a little truth to it) that guitar players are the biggest suckers in music.
I have a very old Ibanez classical with a solid cedar top and rosewood back/sides, fingerboard, headstock overlay, and bridge. The finish is perfectly thin, and you can see both the distinct streak/stripe(?) pattern of cedar, and the pores of the rosewood when you shine a light on it. It sounds and plays fantastically (after a little TLC).
I have taken home various guitars from work for comparison (from $700 to $2600) where I have made A/B recordings and sent to my closest guitar comrade, him and I both choosing the Ibanez every time (though only he went in blind). In fact, I was really hoping he would say that the $1500 Furch was superior, because I really -wanted- that guitar to be better than my Ibanez and needed justification. I suppose that I too am a guitar fool, who would rather WANT a more expensive guitar than be satisfied with what I have.

This Ibanez was a christmas gift from my father when I was in high school. He picked it up from a charity shop for around 20 bucks. It's got, and has had since before I got it, a considerable crack between the back and sides on the lower bout, which is why it's been in the shop for the last 3 weeks. I hope I get it back today!

For some reason, this guitar is completely worthless on the market.
Perhaps mass production at the time (70s) means it's too available? Even so, shouldn't everyone want one?
Similar or identical models pop up every now and then, and even in PERFECT condition, they won't be listed for more than $100. Hell, $50 seems to be the going rate.
I don't get it, but I won't complain either. I've bought a couple of guitars off of customers with similar predicaments for $50 at the customer's suggestion. I don't make money "flipping" them (and it is not my intention), but it does mean that I can get a very very good guitar for next to nothing.

[Gitterbug]

I've had an Ibanez AW-15 cutaway dreadnought with solid cedar top and electonics, for well over a decade. Bottom of the line, perfect build, perfect tone, both acoustic and electric.