Try
http://www.lakelandcampingbarns.co.uk/barn-map for some cheaper camping options around Kendal, the camping barns have camping available as well... specifically
http://www.lakelandcampingbarns.co.uk/barns/wythmoor-farm-camping-barn and here for
http://www.independenthostelguide.co.uk/map-of-hostels-in-the-lake-district.php some more... £8.50pppn in the camping barn so camping should be cheaper.
Glencoe - hum - not much wild camping really simply becuase of its popularity, size and number of walkers and the campsites there are quite expensive. We have used the Red Squirrels campsite in the past, out of season it was quite, in season I think it would be a nightmare, but the Clachaig Inn has in the past allowed camping as well, otherwise you would be down at Bridge of Orchy or just passed the Inveroran Hotel by the 1st bridge there is some great wild camping, otherwise Glen Orchy. thinking about it we have camped at the King's House Hotel in the past as well, so you could consider there - can't remember how much, but there are toilets and a good bar... and you can camp on either side of the road strandling the river, so you can get away from the hotel and be out of sight. I have also camped down in Glen Etive, but in the winter when you don't have to worry about midge at -15C.