Where can I get camber plates?
Hotchkis made some for the RSX, but I am not sure if they still do.
If you have stock or koni, then Ksport, ground control or Kmac are your only options. GCs are a PITA to adjust because they adjust underneath. Ksports are ok, but some people say they are kinda cheap, but for $175, they aren't a bad deal. Kmacs are balla and give you caster adjustment.
If you have teins, then they have a set too, but must be modded to fit with other suspensions.
First you have to tell us what suspension you have already. Also, if you get a set of camber plates, you can swap them from left to right to gain more caster, but you often lose some minor camber adjustment.