I need to find A sight with good dresses at low prices ?

I am looking to buy a dress to go out in, I am not sure exactly on what I am looking for but it needs to be wuite trendy. I need some clothes sites that sell really nice dresses and clothes but at good prices I dont really wanna be spending 50-60-70 quid on a dress. 10 points to the best answer all ideas welcome xxxxxxxx