I have no idea if that's high mileage for it's age or not, but what is usually most important is how well it was maintained. Most longarms can run forever with proper maintenance. Did the owner oil the machine regularly as instructed? Did she clean and oil the bobbin race with each bobbin change? Don't ask these questions of her directly. Instead act like you know nothing and ask "What will I have to do to properly maintain this machine?" and see what she says. Find out if how often she quilted. Did she quilt only for herself, or for others as a business? Did she quilt all day, every day? If there were other previous owners, what were their habits? You could also call Avante and pose your question to them. They may know how many stitches a part-time or full-time quilter puts on yearly.