i'm a canadian leftist, so one might expect that i should be in favour of strict donation limits and whatnot, but i'm actually very libertarian on the point. i've seen some of the ads run in the american primaries. the truth is they don't work - you get no turnout. but, if they did work? you'd have to give up on pretensions of being a democracy. you'd have to hand in your democracy card. that would be it.
if candidates can run these kinds of ads, and they work, the country doesn't need campaign finance reform. rather, it needs educational reforms at the primary school level, with a particular focus on stimulating critical thinking.
so, i'm ok with just about anybody paying anybody for anything so long as a few simple rules are followed.
the first is that voters need to be able to unravel the trail of cash. i don't really care how much the kochs give to who, but i do care that i know exactly how much the kochs gave to every person they gave anything to. so, there should be absolute transparency. then, it's up to me to do the research. that's the only serious rule i think is both appropriate and important.
the only other rule i'd put in place is that funds need to originate in your district, whatever it is. otherwise, that's representation without taxation. which means it's taxation without representation. besides transparency, that's really the only rule i'd put in place.