I looked at truly affordable (a.k.a. "lightweight") fighters and fighter-bombers from the Focker E-VIII to the Saab Gripen recently, but didn't come up with a definitive conclusion worthy of a blog text. The historical success stories are anecdote with no visible rules of thumb for their success.
Instead, I grew a suspicion that maybe the growing importance of electronic warfare has badly reduced the potential for actually outstandingly affordable combat aircraft.
So instead of a real blog post with long text and musings, I offer a consolation prize; a nice documentary about one successful example of a lightweight fighter-bomber; the F-5 (which might have prevented the Gripen's success if its F404-prowered F-20 version had entered production!).