Haha... I know what you mean. And you do make a good point with higher accommodation rates during the festival. But nevertheless, since tickets without camping are not available for sale, I think I'll choose and enjoy camping. Now all I have to decide is which option and if it's worth paying the extra 100 EUR.
I mean even if you don't get the green camping: there are more than enough "calmer" places where you can camp. Just avoid C4 at all Costs ;-) And usually you have to walk a little bit to the calmer places, e.g. 20minutes. But as you are doing that only twice a day, it's fair.
If you are looking for a cheap hotel, then go for a Hotel near the train station. We did that once and stayed for no money at the Intercity Hotel and it was easy to travel with the S-Bahn or Tramway to the event location.