While I do not profess to have the records of manufacturing numbers, I'd bet that for every Nickel Plated Revolver there are at least 10 blued ones. That makes Nickel Plating not only a more rare item, but a more expensive item to produce as well. Back in the day, S&W always sold their Nickel Plated guns at about 5% - 10% premium.
Back in the day, Nickel Plating was in demand for people working in harsh conditions such as marine environments, wet environments, etc. and would typically stand up to abuse and harsh conditions longer and better than blued guns. The NP "killer" I believe was Stainless Steel because Stainless is not a finish - but a solid metal, I think NP guns have sort of fallen by the way side a bit.
Now don't get me wrong...... there's nothing "purdier" than a Colt SAA six shooter in Nickel! That said, the younger generation has grown up with Stainless and has barely seen, handled or shot NP guns. Not only that, but no matter how great the NP job was, it will not stand up or be as forgiving as stainless.
So to get to the point, while most of our lives NP-ing has always been desirable, I don't know if that will continue to be the case. The other factor is simply which one someone likes better - despite the actual finish on the gun. I started off liking NP guns better but now only have 3 left as I have gravitated to blue. While NP may still bring more according to a gun value book, I prefer Blued guns myself and would pay more for Blued guns - same model & everything else being equal. The only exception might be a Colt SAA.
