AA, just looking at the machines from pictures, I have a similar reaction: the first one would be really hard for me to resist. Everything about it: size, condition, features -- and you'd have a machine rarely found in a home studio. Just looking at it would be enough for me to buy it, price willing.
The third would be more intriguing but in a different way. "...2 line lock-stitching in balloons, aircraft work, for sewing celluloid into automobile curtains and for stitching articles of large and awkward sizes. It has an extra long arm and is equipped with a puller feed in addition to a drop feed and will sew up to 6 thicknesses of No. 8 Duck..." is industrial in the sense of the late years of the Industrial Revolution. It would be hard to come up with relevant uses similar to those for which it was designed, but lots of clothing requires 2-line lockstitch. And you are ArchaicArcane, after all.
As for the 2 wheels on the third machine, is it possible it was operated by 2 workers, especially considering the size of what went under the feet (balloons!) and the size of the table it must have occupied?
What a great heritage we're inheriting!