I do think it's incredible how quickly the transfer market normalises new, big fees.
We've definitely played our part, as have other most other clubs.
We sign Mangala for £32m and within 2 years £30m becomes the de facto standard price of a top CB. I think before he moved, there'd been 2 £30m+ CB's - Ferdinand and Thiago Silva. Now there's Mangala, Bailly, Lindelof, Bonucci, Hummels, Otamendi, Stones, Mustafi, Luiz (twice)...it's just the norm now.
Juventus spend £75m on Higuain, and the price of a top striker becomes £75m+ - see Lukaku, Morata and asking prices for Bellotti.
We've spent £50m on a new fullback and now that will be the price demanded of an English club for a top class fullback.
It seems that it really doesn't take much at all for the market to set a new standard price, and then stick to it, and I think it really benefits anyone who is prepared to go first, as you know that short of going really way, way out of line, the clubs around you will normalise the fee within a couple of years.