As has previously been said, really only you can say if she's worth £300 ph. I've seen Emma twice and had a great time and have no regrets about parting with the cash. But at the same time can totally understand others saying there no way they would pay that when they could get a good girl for a third of the price.
I'm a big fan of Emma's porn work and it was a big thrill and a fantasy fulfilled to fuck her. She gives a great service and is a really nice girl.
If you're a big fan of hers when your cock is between those huge tits or when you're banging her with her legs over your shoulder the sting of the cash won't register.