I've got tracks on the two versions of the 547s. They're out of date but you can see the trend pretty clearly in this chart:
Here are the tracks:
Smith & Wesson 547 3" RB Revolver in 9 mm. Bluebook of Gun Values (30th Edition) indicates between $675 in 98% condition and $775 in 100% condition for this gun. I have 41 recorded prices for this model gun from $500 to $999 over a period of 6 Yrs 0 Mos ending May 7, 2008. The average price as of that date was $749. No refurbs, no refinishes, regular sights, all represented as 95% or better, no distinction for engineering revision, if any, no special editions, no distinctions for box, papers, tools. Current or last MSRP is $317.
Smith & Wesson 547 4" SB Revolver in 9 mm. Bluebook of Gun Values (30th Edition) indicates between $675 in 98% condition and $775 in 100% condition for this gun. I have 34 recorded prices for this model gun from $450 to $995 over a period of 6 Yrs 1 Mos ending November 10, 2008. The average price as of that date was $620. 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.