Where to buy bitcoin from?

I Was just about to buy it on Blockchain only £20 worth , but then i realised they were feeing me for half the bit coins (e.g if i brought 0.0090000 i would only get 0.0047583) so i would be receiving £10 worth , is that suppose to be right?

go to localbitcoins

It doesn't look right, I bought a lot of times with them and they never charged me that much.