I strongly suspect that is how some of the bigger "open source" organization (eg. MySQL) make money. They release open software, but then offer support (eg. programming, problem solving) for a price. And why not? After all, "open source" doesn't mean "free support".
And there is nothing to stop proper contracts being drawn up, to provide agreed-upon levels of support, by competent staff, to support the underlying code. None of that violates the open source concept.