A lot of ppl on this forum will probably make you eat your words but each to their own. yes the cheaper tires last longer as they have a harder compound which effectively means less grip, but yes they will last u ages if u drive sensibly, but in an emergency or in the wet I wouldn't bet my life on it. The higher end tires have a softer compound, more grip and wear quicker.
Ever play Gran Turismo and wonder why they grade tires hard, medium, soft and the soft racing tires are always the most expensive?