Let's face it. VERY FEW vintage machines are what I consider "valuable" in monetary terms. With new sewing machines costing up to 10 grand, a vintage machine that costs in the $20-$400 range is not what I consider valuable. Most of my machines cost less than a good dinner out and a few of them, a few good dinners out. I love my vintage machines, but I USE them and will continue to do so. I will be putting my mark and wear on them. I agree that a quality restoration won't take away value...because most are not worth much to start with! I guess it's all relative. I'm not rich, but I really don't think $100 for a tool is all that much if I USE it. Anyone been to Home Depot lately and have seen the cost of "tools"?
The problem lies in a quality restoration. People who blob house paint on machines to cover up blemishes are just making it worse. If you have the skills to have a beautiful end product, go for it. Most of the quality FW repaints I've seen have doubled the "value" of the machine. I tend to leave the machine as is, because I enjoy the history of the machine and know I'll be putting my own wear on it. But, I will absolutely refinish a machine that is far gone, if I bought it for a low price and think I would use it more if it were spiffed up!