As long as the tires meet or exceed the stock load, speed, and size requirements you can run different brands on the car safely. But the differences in tread dynamics, wear, temp, and traction ratings will more than likely make for a performance nightmare.

Assuming cost is the root of your problem: If you can't afford a new set of performance tires for your sports car... perhaps you would find life easier in a car with less demanding maintenance requirements?

Just a thought.