Most sewing machine stores sell refurbished machines that people have traded in, which could be a way for your father to get a higher quality machine for less money. I've also found that most sewing machine store employees are pretty helpful if you go to them with specific questions. Might be worth it to check out any sewing machine stores in your area - tell them exactly what you want, and they might be able to help.

Good luck to your dad! Is he sewing ultralight backpacking gear? My father and I go backpacking together, but with the exception of one cuben fiber rain cover for a pack (which technically we taped, not sewed) I've mostly decided to let the experts do the technical sewing. My time is better spent quilting. :P