I would tell her to buy a good used machine. The old machines have the basics. Older machines typically require much less maintenience, partially because they have all metal parts. Yep they are heavier , but that is because plastic weighs less. There is a reason that so many older machines are still in service. Easy to repair, and simple operations( no computer). Computer machines are sensitive to humidity, magnets, and typically cost more to repair. I have several machines, the old Non - computerized machine is the most reliable.
She can get a great older machine for less than $200.00. If she goes to a sewing machine shop ( a sew and vac) they will offer some kind of warrenty and will have "tuned" it up prior to selling.