from what i've found on sites..
plate - thickness for 20kg - price
Iron edge normal - 65mm - $200/pair
iron edge premium - 54mm - $290/pair (50.4mm hole)
GD muscle motion - 65mm - $190/pair
GD black bumpers - 86mm - $180/pair
SMAI - 85mm - $264/pair
garage Gym (G2) 60mm? - $280/pair
hercules (china) ????? - $308/pair
Body iron ??mm - $180/pair
Werk san economy ??mm -- $330/pair
Werk san IWF certified ??mm -- $380/pair
Pendlay econo V2 ??mm -- $190/pair
Pendlay Black L33t ??mm -- $250/pair
Pendlay colour L33t ??mm -- $300/pair
others?