I dont know the exact numbers of the S-lens production, but 900-1000 range sound reasonable. Several of these lenses, mainly 50's and the 85 was also made in Contax Rf mount so that might skew the numbers somewhat.
As for them becoming "collectible" I dont know. These are modern lenses and their collectibility status depends on the continuing popularity of the Nikon Rf's and the R2S/R2C.
Some of the lenses are already sold out, the 35f2.5 and I think that the 28f3.5 is getting low in inventories.
Lenses like the 50f2.5 was produced in lesser volume - most likely less than 500 as the user's are enamored with "speed" - wether they need it or not!
Cameraquest's package of the three lenses, 50f1.5, 50f2.5 and 85f3.5 is significant as that was an "emptying the warehouse" action. Of course, once they are sold out there will be some moaning and groaning from those who did not snap up this package @ $500 and have to pay "scarce" prices for them!!!
I have the full complement of these, mainly because I did not want to be in the situation to have chase them down at inflated prices later!
Case in point: A 25f4 Nikkor will set you back anywhere from $1200 and up. The Cosina version is 1/2-1/3 of that - and it is a far better lens optically. I know, I have the original and the Cosina one. For "retro look" the Nikkor one is fun, but you really have to like the fall-off and weird aperture control!
The 21f4 is less than 10% of the price of an original Nikkor - and, yes, it is a better lens. It all depends on wether you are a collector or user!