Yes, there are fewer sellers with bulk stocks of NOS spokes than a couple of years ago. I used to be able to buy bulk packs of the grey "Union" brand spokes for the 26 inch wheel 3-speeds without much trouble on the usual websites (eBay, CABE, Ratrod, etc.). The Torrington double-butted were always more expensive than the Union straight gauge, but you could find both. When I started looking for spokes earlier this year, the NOS spokes were being sold in small quantities at insane prices.
It used to be more economical to buy the NOS "grey" colored steel spokes than it was to buy brand new Sapim or DT Swiss stainless. Now it appears to be the opposite. I built my most recent set of wheels with Sapim stainless double butted. I have at least 3 more wheels to build this fall and I'm probably just going to go with DT Swiss or Sapim stainless if I have to buy spokes. It works if the rim and hub are very clean and the new stainless spokes match the condition of the other parts. But if you have very old or worn hub shells and rims, the old stock grey ones match much better.