Great to have you here! If I'm not, (and I may be) incorrect.....the 3940 floor plan ended with the 2014 model year. I have owned a Canyon Star, and they all are good coaches regardless of floor plan. They are built the same way by the same people along side the King Aires (Newmar's TOP model $1M coach). The mileage is great on the unit you're looking at, and the price is about right. You can probably dicker a little on it which the seller probably expects.
Is this a private seller or dealer?
What year are you looking at?
Bottom line, it's a good coach. It's hard to go wrong with a Canyon Star, arguably the best gasser out there in it's class. Good luck to you