That's a terrific price, as far as I can tell. The extractors are very tough, mad of beryllium. I believe you can still get replacements if you ever should need them.
I corresponded with S&W about acceptable ammo and was told any commercial 9mm ammo up to and including Plus P.
Here are my tracks and chart for both versions of the 547:
Smith & Wesson 547 4” SB Revolver in 9 mm. Bluebook of Gun Values (32nd Edition) indicates between $575 in 95% condition and $775 in 100% condition for this gun. I have 45 recorded prices for this model gun from $450 to $1299 over a period of 7 Yrs 3 Mos ending November 11, 2010. The average price as of that date was $694. No refurbs, no refinishes, regular sights. All represented as 95% or better. No distinction for import location or engineering revision, if any, no special editions, no distinctions for box, papers, tools. Current or last MSRP is $317.
Smith & Wesson 547 3” RB Revolver in 9 mm. Bluebook of Gun Values (32nd Edition) indicates between $575 in 95% condition and $775 in 100% condition for this gun. I have 56 recorded prices for this model gun from $500 to $1295 over a period of 6 Yrs 11 Mos ending July 5, 2010. The average price as of that date was $772. No refurbs, no refinishes, regular sights. All represented as 95% or better. No distinction for import location or engineering revision, if any, no special editions, no distinctions for box, papers, tools. Current or last MSRP is $317.
And the chart. Keep in mind the trendlines represent averages, better examples would command higher prices, especially with box, papers, tools, etc.