Okay guys what should I expect to pay for this gun used

Depending on condition, anywhere from $350-600, for one in good all the way up to excellent condition (unless it was one of the special issues). At least that is roughly what we see them running for up here.

Early year's, say before '78 or so tend to run much higher if in good condition.

If it is near mint I would say $500-$550 for a standard model. No dents or scratches.
SPAD