I think one thing that hasn't been considered here when discussing the price of tyres is rim size, load rating and speed rating. We all know that when fitting tyres to a vehicle, by law you must fit tyres that equal or exceed the manufacturer's specifications as shown on the tyre placard. In my case, that means 19" rim size, a load rating of 98 (750 kg) and a speed rating of W (270 km/h). Now, there's no way I'm going to drive anywhere near that speed, but I have no choice if I wish to remain legal (and have valid insurance).
All these factors combine to make for a pretty highly spec'd tyre, and they don't come cheap. Yes, there are some sub-$200 tyres that meet the specification (in theory), but they're made by brands I've never heard of. Any tyres that do meet the spec and are made by a reputable manufacturer cost in the mid to high $200's, and up to $400 and beyond. Even the OE Bridgestone Turanza 001's are around the mid-$300's. So I reckon getting Michelin Pilot Sport 4S's, with their superior handling, safety and comfort for just over $300 per tyre, was well worth it to me for peace of mind alone.
As someone above said it's horses for courses, but when winter comes, it's dark and wet and some silly sod does something stupid necessitating quick action, I won't be thinking of the extra few quid I paid per tyre -- I'll just be glad I've got the best rubber on the road that's presently available at a reasonable price.