Tyres are like all things in life, "good things not cheap, cheap things not good!!" Most of the premium tyres, Michelin, Continental, Pirelli etc are very similar in performance and price. The cheaper tryes have their limitations, you can't expect a tyre that costs 50% of a premium tyre to perform the same.
There are some good reviews here:-
http://www.tyrereviews.co.uk/
Rick