First of all, there's no book that can give you the definitive "value" of anything. Value is an entirely subjective term, and relative to both the individual and where he is.
In real terms, nothing is actually worth more than what you can get someone to give you for it on any particular day.
Both the supply of and demand for a particular item in a particular market area are what drives its price. Only you can decide if the price being asked is what you're willing to pay to have it.
Bear in mind that someone with a different opinion might happen across it while you're making your mind up, in which case he'll make the decision for you.
I've owned and carried an exactly similar 9x19 for about 15 years. It has served me well. Nothing has broken or worn out with extensive use. The finish is both tough and highly resistent to corrosion.
It is relatively heavy for its size by today's standards. This doesn't bother me personally, as I carry it in a Sparks IWB holster. The weight makes it very easy to learn to shoot well quickly with, IMO.
Mine has been both extremely reliable and quite accurate with its prefered loads. FYI, the stock sights on mine were regulated for POA/POI to coincide with 124 gr. ammo. 115 gr. impacted significantly lower even at 7 yds. YMMV.