In Rosthwaite, you can camp at the youth hostel
In Shap, you can camp at the New Ing Lodge for £7, if that helps?
In Keld, Park Lodge Campsite would cost you £6 if you prefer not to wild camp.
At Clay Bank Top there is Lord Stones Cafe and campsite however it's expensive as you are charged for 2 people even if you're on your own.
All sites have websites if you want to have a look.