It's an interesting German side-story.
You wake up one day and decide as a German citizen...you'd like to run in your district for the Bundestag. Naturally, it helps to be part of the party apparatus. You walk in and have a conversation. They let you know right up front....for the next election....you need to have 70,000 Euro in your hand. That's the typical average cost of a localized campaign. My guess is that in more urbanized areas (like Dusseldorf or Munich), you could be look at double that.
You go and talk to experts on the matter, and they kinda hint that 70,000 just gets you into the general field....that 100,000 is likely a better figure to aim for, and plan on spending.
For most Germans (probably in the 80-percent range)....having a hundred-thousand Euro to spend on a 100-day campaign is just not possible.
A grassroots campaign for less? Maybe if you had dozens of volunteers (students, neighbors, friends, etc)....you might be able to do this for a lot less.
I sat and watched a public TV program last month which talked about two small-town candidates and their efforts for a mayor campaign several months ago. In both cases, they went out and hired a special guy who has handled a lot of small town elections. He came in...spent an hour taking pictures of them around town, and produced a brochure (to be handed out in the village). He worked their speech, and coached them on oral presentation. Charges for his services? Kinda left out of the show, but I would take a guess that it was in the 10,000 Euro range.
If you make it to the Bundestag, your salary level is between 8,500 to 9,000 Euro a month. But you can do the math and figure....every four years....you have to find 100,000 Euro to run a decent campaign. Donors of importance? You can't help but look at the interaction with donors as being now a critical part of the whole process of politics in Germany. Making a promise here and there....helping to hire someone's son to a city job, or ensuring a city contract goes a certain way....all helps to pay back the donor in the end.