NEVER drilled, and NEVER eBay unless you KNOW the manufacturer is legitimate, and trust the seller.
Slotted from a GOOD manufacturer is worth it.
FYI, drilled rotors don't increase warping issues, they cause cracking and breaking issues. Drilled rotors are for one-time use on the track, and for street use are for ricers that don't know any better.
On a REAL car, drilled rotors are a bomb waiting to go off unless the rotor diameter is increased enough to overcome the issues, and the holes are CAST into the blanks, rather than drilled.
Remember that HOLES decrease SURFACE area as well, and will decrease braking performance unless rotor diamter is increased also.