Smith & Wesson 686 Plus 2-1/2 in Bbl Revolver in .357 Magnum, .38 Special, Plus P. Bluebook of Gun Values (31st Edition) indicates between $375 in 95% condition and $650 in 100% condition for this gun. I have 81 recorded prices for this model gun from $350 to $900 over a period of 6 Yrs 8 Mos ending February 16, 2011. The average price as of that date was $537. 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 $964.
Here's how the data charts out (below). Note that the Average Price trends out at nearly $620 as of February 2011. Better examples of the model would command higher prices, especially with box, papers, and so on. I have a 686-6 Plus and it is a fine revolver, no problems at all.
If the revolver checks out well, it will be as good as any you can find. %565 is a good price.