You called?
I 'm a year behind on any newer prices and I've looked a few times without finding any. The 3-in 547 has seemed to have declined slowly in average price for a couple years with the 4-in SB rising somewhat during the same period. As was posted, the 4-in is the rarer gun. Maybe that explains it. Neither is showing up very often.
My track:
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 40 recorded prices for this model gun from $500 to $999 over a period of 5 Yrs 11 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.
Here's how the data I have charts out. I'm guessing the trend to be right around $700 for an average 3-in 547.
Here's the one I had, with Hogue Bantams to save my knuckles (I kept the regular stocks, of course, and sold them with the gun a couple years ago).