I was lurking the forums and it seems like the discontinued Seiko calibers (eg the early divers, the automatic chrono, the jeweled 7A series) are more sought after. And it also seems generally they are also much well-built, lasting decades.
I was wondering when the early folks bought the 6105 or the 6138 etc, they bought it with just a thought, "Hey, I need a watch to dive / to tell the time." But little did they know that the $100+ watch they bought 30 years ago would worth easily 3-5x the original price now.
If I were them and IF I can forsee the future, I would stock up on the early divers, the auto chronos etc. Not very expensive to buy 2-3 different design of the same caliber anyway!
Will the watches we buy BNIB today become the sought after piece 30yrs down the road just like the early Seikos diver or auto chrono? Nobody knows and it will be interesting to keep track and see what happens then.
So go ahead and buy the different colors of the Monsters, Knights, SKX divers etc! You may hit the jackpot few decades later!