Haven't commented on this thread before now, but just wanted to say a few things.
Firstly look at the schools themselves, not the sector they are in.
Also nice buildings may be more inspiring to you, but you're not the one going to school. Your dc may well be inspired to achieve from other factors.
There are many crap, underperforming state schools, but these are not the majority. There are also plenty of high achieving state schools with inspirational teachers, good results, well behaved children, good facilities and plentyof extra-curricular interests. Saying they're all crap is like saying all non-selective private schools are just full of thick posh kids.
IMO if you geniunely want to go down the private ed. route, but are short of funds, I'd say save the funds till secondary.
Finally I think your feeling is that if you pay fro something it automatically must be better than the free alternative. This is just not the case. Without meaning to sound patronising, I think your fixation on websites, brochures, results etc, rather than anything less tangible like how you feel your child would fit in, is because your background isn't one where education was valued, and therefore you don't feel confident enough in your ability to make the right decision. So you analyse hard facts, because they can't be augued with, rather than looking at the whole picture.
HTH