I think Diplomats are a bit rarer than Aristocrats because their production lifetime was shorter. They're also considered to be better shavers by some. I think they'd average out to be maybe twice the price of an aristocrat. But lately they seem to be going for very low prices. Like this one for example:
The Diplomats are great shavers. I found one in excellent condition with no plating loss for $25 shipped. It wasn't labeled as a Diplomat and they are often not listed correctly. They seem to be essentially gold plated Presidents without the exorbitant price tag the President commands.
Lots of diplomats recently. I put a bid in on both of those above, but never got around to bidding again at the end. Finally won this one today though. I would have passed on this one, but after seeing how well Mr. Scruffy's razors cleaned up, I figured this one would come out fine.