What a great gift to give your Mom
. I would suggest you decide on a price you are willing to spend, visit the dealer & see what deal he/she will offer on different models, warranty & including machine classes. Many dealers are having a 25% off sale on feet right now & many are doing end of year inventory sales. A "walking foot" is one I'd suggest buying with the machine for quilting. Bernina's aren't cheap, but a 2nd hand machine normally goes for half price or even less, depending on the dealer. Then take your Mom shooping & let her chose.