Sometimes free - sometimes a small fee, depends on time of year / public holidays etc.
Generally I think if there is a skip bin at the entrance, the ranger will be around for the fee.

A very basic camping spot situated where Marrinup townsite used to be until the 1961 bushfire that wiped out it and another half dozen timber towns in the area.  BYO everything - including toilet paper!

There are long drop toilets,  a few fire rings and picnic tables and it is only about 5 kms from Dwellingup.
Caravans often pull up along the tree line while camper trailers and tents use the open space away from falling branches.

Nearby is the Marrinup Falls walk trail.  Class 3 means a bit steep and slippery in places but most people will manage it if they take their time. 

Fire restrictions November - March means you cannot use heatbeads (a solid fuel) during summer. 

Travelling between Pinjarra and Dwellingup, turn onto Grey Road about 5km out of Dwellingup.
Travel about 5km along this dirt track and turn right over the railway line, travel about 500m and take the right hand fork.  You will see the main part of the campsite about 100m up the track.