hi Mimmi ...
it is nice to do camping... but often you have to use a bus (or walk a long way) to get from the station to the camping area.
if you use a normal, simple camping area (2 stars are enough), you can sleep there for under 10 EUR.
it is really cheaper than a hostel. but in the bigger cities, it is easier and safer to use a hostel - or you leave the city at night going outside to a smaller town or village and there to a camping area.
don't forget... a tent will have a weight around 3 kg ...!
my opinion: more weight in your backpack, but a cheaper travel.
have a lot of fun,
information about hostels and camping: rail.cc/en/where-to-sleep