You can never have too many! My wife and I have our collection of 33 machines (including 12 cabinets) in our little frame home. It’s crowded, but there’s always room for 1 more.
Photos and descriptions of them are on 5 web pages beginning at:
http://thayerrags.com/sewing.htm
(none of these machines are for sale, at least for the time being)
We also have 7 more machines in use at the shop, and as of today, I have 312 parts machines and 30 parts cabinets/stands/treadles (stored all over town).
CD in Oklahoma