How do you define too expensive?

A lot of posts involving multiple RVing issues involve people saying this or that is overpriced. How do you make that determination? There are posts where people say they won't stop at a certain fuel station because the fuel is overpriced and they can get it cheaper elsewhere. In my experience, there is seldom more than a $.05 difference in fuel prices between neighboring fuel stops. In my car, that amounts to around seventy five cents. In my truck, about a dollar. My motorhome, maybe four dollars if I have driven it to nearly empty. None of those amounts are enough for me to forego convenience to go elsewhere.
A recent thread concerned KOAs. Several posts said they always avoid KOA because they are "overpriced". But how much more does a KOA charge compared to a similar non KOA branded park nearby? Is it a couple of dollars? Is it more than five bucks? I don't think it is much more than that. I understand completely if you are saying KOAs are more than dry camping and you are equally happy with or without hookups. But will you really gain anything driving around with your rig that gets 7 miles per gallon looking to save three Washingtons?
Finally, what does anyone learn when people post a price they paid and then having that price held out as proof an entire franchise is overpriced? So you paid $60.00 at a KOA. That means nothing without context. Where was the park? Sixty in the middle of Kentucky might be high, while sixty on the coast is pretty dang cheap. What time of year invokes the same matrix. What hookups did you require, the makeup of your rig and the makeup of your group all influence pricing. Without all the information the $60.00 fee is pretty meaningless.