Please accept my condolences on the passing of your Mom.
Are any of you interested in the equipment and other supplies? (any or all of it?)
If yes, would you be expected to pay for it?
Is there any paperwork available/around that can tell you how much she paid for it?
From what I can gather, most Bernina machines hold their value fairly well -
I am guessing that if your Mom had a long-arm, that she had a lot of other sewing related things?
My first suggestion would be for you to use her items yourselves.
Goals?
Just to get the room cleared as soon as possible?
To recover some of what was spent over the years? (You probably don't even want to know - I am not excited about having my family figure out how much money is tied up in my "inventory"}
The important thing is - did she get pleasure from these things and working with them.
Would it be sensible/possible to just close the room off for awhile to gather your thoughts? Would your father be interested in learning the craft in memory of your Mom? Some men are fantastic long-armers.
Have you contacted the dealership and explained the situation? If the owners of the dealership are kind and compassionate, they should be willing to help with - at least - a cost for disassembling and packing the machine to move it - and packing it.
I think that having the receipts showing when she purchased it and how much she paid would be helpful, also, when talking to the dealership.