There is no "average" price but it appears that this model, used (which is the only way to get it now as it has been out of production for years)& in good condition is about $250.00+/-
100-1000 USD depending on specifics
50-550 usd
50-350 usd
S&W has not used 19a as a model designation.
250 or so
100-450 USD or so
100-300 or so
300 USD
50-500 usd
Not recommended
100-300 USD