I have to think twice about my vintage purchases too, but I can't resist. I still have a 201K-2 on my list, and I hope it will turn up at a time when I have the money and preferably locally since transport is always a bit risky.
I am very intersted in one of the early cast iron zigzaggers, a Bernina 117, a Mundlos Victoria (probably the first domestic zigzagger). They take regular needles.
I have hesitated a bit about the 401, they turn up now and then, and one went within a day at a local charity shop a few weeks before Christmas; less than £30 in a small table. Most go for around £50-£100. If I didn't have a Bernina 730 and an Elna Supermatic I would probably have taken a chance on the first I came a cross.
Roger has this industrial straight stitcher in a nice cabinet within reasonable size. I am still envious ;- )
If I add the Featherweight, the Grasshopper or another neat light weight portable with a clever design, that's eight more!
I have not forgotten the early Singers with rose decals, or the Gritzner with floral art nouveau decals...This thing never ends, I haven't reached the old German developments yet. I'm not expanding beyond my book shelf capacity until I have a heated barn for storage, and before that I aim for some very nice pieces of furniture :- )