Quite a few assumptions here.
In our case we paid between £30 and £50 every night to stay on a campsite.
We ate brunch at some super little places that DH had researched and found beforehand - Nanny's in Shieldaig was standout, as was the Store Cafe in Coldbackie - visited castles, went to Orkney - spending money on taxi, ferry, 3 cafes/pubs, coach trip, Italian Chapel, Skaill House and Skara Brae in one day. Visits to local deli's, pubs (Applecross Inn was great), restaurants (Lucano in Kirkwall and Clachan Grill in Ballater were stand-outs).
Driving more than competently on the NC500, being ultra cautious with passing places (had absolutely no issues - people were considerate and polite, as were we). Made sure to only stop at designated viewing points.
Did a wonderful tour of Lochnagar Distillery - and spend far more on whisky than a few nights in a B & B would have cost us!
The only judgement you made which is correct is that we filled up in towns.
We met some really pleasant and interesting people - locals and other travellers - and had a wonderful trip. Even the weather was pretty good!
On a totally different note, I am sure that I saw a black panther type of animal leap across the road ahead of us, fairly close to the Castle of Mey. Anyone know if this is an area known for sightings of big cats?