Most attendees of estate sales expect rock bottom prices. Add to that Kenquilt is no longer in business so a prospective buyer has very little resources available to them to learn how to operate, trouble shoot, even setting it up. And if the seller can't help with that not many are willing to invest a few thousand unless they are already familiar with midarm or longarm quilting machines.
another option for your friend if she can't sell at her estate sale is to post it for sale on one of the many websites out there. Here are a few to get you started:
https://thelongarmnetwork.com/pre-owned-longarms
https://longarmuniversity.com/MachinesForSale.html
And there is also FB pages, Craigslist, etc.