I guess my question is... does your son have a wood shop? Would he be happy with a 300 dollar table saw? A 300 dollar lathe? I am not an advocate of multi-thousand dollar machines, I work on a 40 year old Bernina that I picked up for 350.00 just serviced at a sewing machine canter. A trade in I am sure on a multi-thousand dollar machine. But then again, I looked at the machine, listened to the machine, bought it from a reputable dealer who stood behind his work when I found it sewed crooked. Fixed it right and 9 years later, still runs like a top. Convince your son to either put in the time to learn about what he is buying used or pay up a little more for a mid-level machine with a good reputation.
tim in san jose (who appreciate good tools and throws junk ones away)