I think the world is divided into people who collect and people who don't!
I was born to be a collector and showed it during my teen years when I asked my parents to transport my Seventeen Magazines that I collected from about 15 to 18 years old...they did it for me and it wasn't until years later after I was married and had a son that I finally told them to send them to the trash! LOL
I think it's hard for some to understand that thrill when you find a certain something to add to your collection and it isn't always rare and unusual but it's just the right one.
As for quilters who want Featherweights...in a way it's a sort of fad to have one...and I do, but many times when I go to a workshop or class I end up needing the machine that does the best applique stitches which ends up being my Viking not my Featherweight. I also have a 301 which is a great substitute for a Featherweight and it has the virtue of being able to lower the feed dogs for free-motion quilting too.
Getting back to your collection it's wonderful that you have the space and the skill to have all the machines that you have right now...hope that you do make a file with all the pictures and accessories for the knowledge that you can pass on.
God Bless and share more when you have things the way you want them....until a new baby joins your herd! LOL