Newer SRK members have to understand that the Seimitsu parts are NOT as popular as Sanwa because a) more people have used Sanwa in the past few years; and b) Sanwa parts practically monopolize the whole competition-level joystick manufacturing industry!
There are occasional production runs of joysticks with Seimitsu parts (usually an exclusive HRAP SE; pretty much exclusive to Amazon-Japan after the HRAP V3/VX SA debuted) but those run in maybe a few hundred – very limited edition (500 or less… maybe). With the costs of importing any joystick from Eastern Asia, it’s generally cheaper to just remove and sell (online) your stock Sanwa parts from any production joystick and install store-bought Seimitsu parts from wherever you can find them. Thankfully, the Seimitsu joystick levers have become more popular alternatives to the Sanwa JLF which a LOT of us have problems with but the Seimitsu button line isn’t supported as well in the US/Canada; people generally stick with Sanwa pushbuttons or get the specialty Seimitsu buttons like the Skeleton editions for artwork and screw-on buttons in place of plug-in buttons. Seimitsu definitely has an edge on Sanwa in variety of 24/30mm buttons and a definite price edge with regards to transparent buttons.
Nobody, and I repeat, NOBODY, is making anything like a production Seimitsu joystick. The company’s popularity peaked sometime during the 1990s when a FEW joysticks were manufactured with Seimitsu parts or Seimitsu knock-offs (Sega Saturn Twinstick, Konami Hyper Stick, some production Capcom CPS Fighter, Sega Saturn Virtua stick revised/“candy edition”) and since then Sanwa has dominated.
I know that Arcade Shock imported a limited number of Qanbas with Seimitsu parts (LS-32 control lever most likely, Skeleton buttons) but I don’t think they have sold out of them… The popularity level just isn’t there for a mass-production SE joystick.