Solution: Only a candidate can pay for ads, campaigning, and the like. There is a campaign contribution cap reasonably low as your average citizen could reach it. None of these BS PACs, none of this "I'll make a large donation if you 'listen' to what I want".
What happens in the rich candidate vs poorer candidate elections then? The richer one would get a lot more viewership and exposure, increasing his chances to win.
The problem, of course, is that the courts have struck down similar (actually, less restrictive) laws. So it doesn't seem as though there is any path that would lead us to that from where we currently stand.