If you're getting coilovers for performance, I would probably look elsewhere. imo, it's almost impossible for a company to design a good performance coilover when their products are not used in any form of organized professional motorsport. The brands that people have positive experiences with time and time again are the ones you see on real race cars.
If you want to slam your car, cheap coilovers will get the job done. If you want it to truly perform, then it is probably worth it to spend the extra cash. Keep in mind that it is common practice to reduce cost by designing one coilover and simply welding on different mounting brackets for fitment on a variety of cars. The problem with this is that so many cars are so different in their handling and weight distribution to begin with, so you don't get an ideal solution.