You'll have to be the judge on this as there is no way that someone in the US can say if that's a good price for the Philippines. In the US a used 686 can be brought on average for less than $650.
The 686 is a great revolver, but you also need to know that what's being sold is a 686 "no-dash", which is the first year production version. The 686 no dash and 686-1 was the subject of a recall by S&W.
With certain types of .357 magnum ammo , typically a high velocity lighter weight bullet load, along with a soft primer, would case the primer to "flow back" into the firing pin bushing hole and prevent the cylinder from turning, which caused the gun to become jammed. Now this wasn't a wide spread issue with the early 686's, if you stick with the regular 158gr. bullet weight ammo, there shouldn't be a problem.