The most I have paid for a vintage machine was $25.00. It was a treadle and in running order. It needed a bit of sanding and a coat of varnish. It is a beautiful machine and I have had it for a good 25 years now.
When buying one at a garage sale it has to work. I usually pay $5-$10 for one. I have also had a number given to me and they were all in working order. I have no more space for another machine right now. I am always watchful for other machines that I just can't pass up so I can't say I am finished. I just have to make space for another machine then.