BEagle, I suppose if someone is doing just a PPL(A) then £450 may be a significant sum. My perception is that a significant proportion of the PPL student community intends to progress on to ATPL. In this case then £450, or £1000, isn't. They will know this if they've been given honest advice up front.
I speak as one who has spent £45K getting a CPL (H), wherein £450 will get you 2 hours PPL instruction and doing the CPL flying test costs £1000 including examiner fees and a/c hire. I am now looking at spending another £25K getting to FI (R) (H)! Admittedly rotary wing flying is ludicrously expensive so one becomes somewhat desensitised to the value of money, at least in the context of flying. However the interesting point is that of all the people I've met doing PPL (H) and CPL (H) few are wealthy and I doubt are any better off than your average PPL (A) or ATPL (A) student and yet they find the substantiallly larger funds required to do rotary wing flying.
Of course, if only one FTO adds £10 onto their FI's hourly rate then it will lose business. However if there was an industry wide move to raise instructors' rates then I don't believe anyone would lose any business.
I may be wrong, but I don't think so.
Your efforts to grant junior instructors half a chance in the face of superior competition are noble indeed.