But if we quite fancy camping? Or is that not a good idea?
It's not a bad idea at all, and can be done very cheaply in many parts of Poland. For instance, I stayed here once - hotel-pttk.pl/pl/camping - not a bad place at all and ridiculously cheap if you want to camp.
You can go much better than that if you look for rooms in private places - last time I was there, you could get a very decent room with a bathroom for as little as 70zl a night. I did stay in one very strange place in Nałęczów though..