The PX sold mostly run of the mill watches you could buy anywhere just cheaper, sometimes.

If you were lucky you got a limited edition or limited production. Those are the ones you see going for astronomical prices used.

Also, when you go into a watch shop and say "how much you give me for this" the guy over the counter is assuming you know jack and will rip you off any way to Sunday. Even if you have a more pedestrian watch and he is really honest he will probably give you half what he expects to get for it.