This is the cheapest I've seen this kit sold by Amazon (not a third party)
Finally ordered myself some of these highly recommended brushes.
The core collectionhttp://www.amazon.co.uk/Real-Techniques-Core-Collection-Kit/dp/B004TSFBNK/
I know there is a third party seller for a few pence less, but I prefer ordering from amazon directly
£20.99 each at boots/superdug