Do you free motion quilt on your Janome? And which model? I have a Singer 9960, but the throat is only six inches - getting a quilt through there is tough and really hard on my shoulders. So I'm shopping. I like the Singer, it works really well - except for the free motion quilt limitation.
I also have a cheap Brother that is 20 years old, and I'm sending off with my daughter for their first apartment. Its ok, but it doesn't do heavy duty well at all. And I have my grandmothers machine - probably original from the 1930s - but it needs repair. It worked fine for a while, but without my grandfather's constant care (he died 30 years ago), it didn't last long. Old machines ARE workhorses, but they often worked so well for so long because someone in the house really KNEW how to care for them. I'd stay away from estate sales for that reason - you might end up with as big a repair bill as if you just went out and bought new if the machine can't keep tension.