What's the problem with the ones you've got. If you're getting the symptoms of being warped (ie pulsing through the lever) then try this mod before condemning them. Put a 6mm bolt and nut through the rivet where the rotor joins the hub mount and nip it up. Spray the rivets with brake cleaner whilst turning the 6mm bolt round with a spanner. Repeat for all the rivets. You'll be amazed how much crud comes out and this sorted mine out.
Taksi