Additional things to consider....
1. Curtains and pillows can be bulky if she's sewing home dec fabrics so be sure the choice is up to that work.
2. If she's used to a treadle, would she be comfortable with buttons and auto settings/adjustments?
3. Older workhorse Kenmore 385 series machines were made by Janome and often found at online selling sites, and sometimes at sewing/vac repair shops (at least near me, sometimes).
Several years ago, my daughter had one of the DC series but complained that it vibrated and shook when she got going. Mind you, she's known for a lead foot on the gas pedal. She sold it and bought a used MC6500. She does a lot of costumes with all kinds of fabrics.