There is certainly an argument for state funding of political parties. If you really want to remove corruption, state funding is a good way to do it. Lets face it we don't want to end up like America where people are doing huge favours for each other in return for jobs/money after they leave office. Although, is that already happening?
My personal philosophy is that private, but capped, funding is a good way of dealing with the problem. I mean capped ACROSS THE BOARD. No opt outs for trade unions.