I have always thought (well, not always but almost) that the RotJ Fett suits were the less replicated ones, being the SE Fett the most replicated, until the Jeremy Buloch year, when ESB became a BOOM, everyone wanted to have an ESB one because JB had one, this was increased with the MR helmets, which have a closer look to the ESB helmet. Then the PP#2 props were released, like the GMH, and right now everyone wants a PP#2 costume, or at least a Sandy "helmeted" costume because of the look/flare of the PP#2 helmet being closer to the Sandy's, with the RotJ costume still being the most forgotten one (of course, after the Sandy/Promo costume/helmet).