Be careful or they will start following you home! Many folks on the Vintage and Antique thread have 10. some have 20 and more. I have about 15 treadles, 1 Howe, 1 white and 2 black 221's, a black longbed 301, and several more. Most are waiting for "someday" to be cleaned up, stashed upstairs. Sometimes I have to put my hands over my ears because I can hear them sighing. The first few I bought for the cabinets- here's something about beautiful old wood and craftsmanship that appeals to me. Then I started being a bit more discriminating in the machines' decals and condition. Some I bought as parts for others. Might be moving to a smaller place in the next year or two, so plan on starting to clean up some and thin the herd (so to speak) over the winter. Some folks collect 1 of everything they fancy, others must have all turquoise, others have many versions of the same machine (301's in different colors and bed sizes).
As for Antique vs Vintage- most collectors consider over 100 years to be antique. Since I'm from the latter end of the Featherweight era- I consider them Vintage.