I don't agree. I've never seen a Temper Orange on the road and when they are advertised they seem to be cheaper. IMHO this is because its a poo colour and very few people want it. Very rare but worth less rather than more.
Its not as simple as saying that the rare colours command more. Its more specific to the blacks and probably the Azures.
As for there being lots of silvers and greys, thats because they are more popular as colours - yes there are more second hand ones but there are also more potential buyers so it won't depress values as suggested.
Harsh
If it helps i quite like the Temer Orange