It's so funny that you wrote that - I just returned from scrounging through my parts bin looking for a pair of these myself for an upcoming build. Luckily I have a brand-new set, which doesn't help you, but does make me wonder whether Paul's decision to stop making these contributed to the development of the Silver shifter Mk II. I have a set of the IRDs on another bike and they just aren't as good as the OG Silver/Sprint.
If I hadn't found these I would have been very tempted to go off in a different direction and buy a Rohloff hub or something. So 5 minutes of scrounging just saved me $1,200+! Not a bad morning's work...
Honestly, stuff like this creates a real tension between my desire to go all Marie Kondo on my parts stash and take back my garage vs. the knowledge that parts that I really like and depend on could go away at any time, reinforcing my hoarding impulses.
Good luck in your search!
Jay Lonner
Bellingham, WA