I have a small collection of vintage, manual and computerised machines. I use each for a different part of quilting or taking to class. I have built them up as and when I needed something.
I would suggest giving your wife a large card with come shopping with me after Christmas you could at this stage tell her where or leave ot dangling. Then take her too a sewing shop with a large selection, new, ex-demonstration models , used models the vintage. I would go for ex- demo, usually they have been in the shop and used by customers to try. In good working order and well cared for. Used may not have been lovingly cared for. A class is vital so can your wife carry the machine you buy. So light weight machines in the bernina, janome groups have different stitches etc.
if she is quilting a quilt does sh require a large throat in the machine? Can a walking foot be used on the machine.
How many brothers do you have , and are any English.?