I'd agree it's a good price. The 617s are hard to find used or new and the four-inch 10-shooter is one of the most sought after. Used ones often sell for as much as new ones.
Here's my track on the gun:
Smith & Wesson 617 Plus Revolver in .22, Long Rifle 4-in Bbl. Bluebook of Gun Values (31st Edition) indicates between $326 in 95% condition and $631 in 100% condition for this gun. I have 34 recorded prices for this model gun from $350 to $795 over a period of 7 Yrs 3 Mos ending December 5, 2010. The average price as of that date was $501. 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 $940.
Here's how the data charts out. You can see the Average Price Trend at about $620 as of March 2010. The chart is one price behind the track, $580 in December 2010 (this month) but that would not have much effect on the trend. Good examples would command higher prices, especially with box, papers, tools, etc.
Bud's price is now $660, cash discount, delivered