I love the idea of open source hardware, but one issue I struggle with is - what happens when one or more components go out of production?

I suppose one solution is that the maintainers could update their component list (which might involve more than one component because of compatibility issues?). But what if I'm in the middle of purchasing the components only to discover I can't get them all? Maybe the maintainers could sell component kits? That might be a nice way to fund their work. Not sure if that would run into issues with IP laws, though.