honestly I wouldnt buy any rotors unless they came from a reputable company, or I was familiar with the brand name. some companys can just go out and buy normal rotors, then drill some holes in them and/or slot them, then turn around and sell em for a profit.
Slotted and Drilled rotors take special engineering to get them right otherwise they will start to crack on you.
I have R1 Concepts rotors. They actually are a reputable company, they just arent a large company. If you just call them (or order though IM, like I did), they are actually cheaper than they are on e-bay. Also, they can machine them however you want; for example, I specified slotted only rotors, as I didn't want to risk the drilled rotors cracking. They didn't charge for the custom work, it just took an extra 3 days to get them.