The attitude of some airfields always suprises me, given the opportunity of having 20 light aircraft at £10 a time or 0 aircraft at £20 per landing, some will opt for the latter, regardless of the facilities they supply.
Fortunately there are still plenty of options for the private pilot who is not constrained by a specific reason for landing at a particular airfield, Norwich, Southend and Teesside, (to name but a few), all positively welcome light aircraft at reasonable prices, even though they all have a considerable amount of commercial traffic to contend with.
QNH1013, I don't know where your information about profit margins on avgas comes from, but the majority of airfield make little or no income out of it. What money they do make is soon swallowed up by the running costs of storage and bowsers etc.