Most rotors are made of cast iron, not steel - I used the OEM replacement Brembo - sourced from Brembo, via Amazon - for less than your NAPA/AutoZone/CarQuest stuff - like Yankee-Tim describes, they'll have Brembo stamped into the edge, but I don't think come cross drilled and "zinc'd" from Brembo, so I'm guessing someone's buying them, drilling them & reselling them on eBay.
I don't see the need to cross drill (or groove) the rotors on these vehicles and I'd be a little wary - the cross drilled holes have a tendency to cause cracks if not properly done.