Glock experts - need your opinion

I can pick this thing up for a good price, I think at least. It's a Glock 22 in 40 s&w. Weird thing though its labeled "San Antonio Park Police". The serial number is SAPPxxx (x's being numbers). The current owner is a friend of my son who took it in a trade and his mom flipped out and is wanting him to sell it. It's in good shape but seems to be missing the trigger safety.



I've been out of the gun world since college, so I figured I'd ask for some help. What price would be right? Is it less valuable due to the fact that it was made for law enforcement?



Thanks guys,







Steve