Cheap ones can be as little as $25 for certain applications (Prizm) more expensive brand name $45...almost double the price. I don't think you can lose with the chinese cheap ones. They won't last half as long. I have yet to get a bad set from the get go.
As long as you torque your wheels evenly. they shouldn't warp
As long as you torque your wheels evenly. they shouldn't warp