505Gibbs and Loner seem to have it covered pretty well. Here's what I have for tracks on both versions of the Model 547. I don't have a lot of recent prices, as you'll see. What I do have I believe is interesting insomuch it shows the 4-inch having overtaken and passed the 3-inch in value realized in actual sales.
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 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 (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 engineering revision, if any, no special editions, no distinctions for box, papers, tools. Current or last MSRP is $317.
Here's how the data charts out. In answer to the original post, the 3-in version Average Price Trend seems to be leveling off at about $800 as of November 2010. Probably a bit more by now. Better examples of the gun would command higher prices, especially with box, papers, tools, and so on.
The 4-in is the rarer version and its Average Price Trend seems to reflect that topping off at about $950 as of November 2010. Again, better examples of the gun would command higher prices, especially with box, papers, tools, and so on.
Note also, the declining monthly price count for each version also reflects their relative scarcity, and they are both increasingly hard to find.
My personal preference is for the 3-in round butt as a carry piece but both are really nifty, strong, reliable guns.
