Re: A bit of a "metoo" here ...
"There's always the Eudora model (free software, support via contract)
The problem with this is that if you're doing this, you _really_ need to pay attention to what the endusers want and deal with the bug reports. Writing things off as "not a problem" or "works for me" doesn't sit well with paying customers."
And, of course, you need to make sure there are enough bugs in your program that people need the support.