Jon
I think even top quality tyres will wear the insides of the rears if you have a camber problem.
I'd say your car has been lowered without any camber correction.
Get Wilkinson Suspension to correct this before wearing out new tyres prematurely. You'll get better traction too.
NO_RESPECT
For a cheapish tyre try Kumho 512's from Wanneroo Tyrepower for less than $200 last time I bought. Sure there is better if you want to spend the money ,depends on how you use the car.
Cheers
Chris