I got an R3 (not R3S!) very slightly used off eBay. It’s easily my best keyboard. If you’re seriously in the market for R3, buy one.
That said, the manual is entirely in Japanese and some of the Fn commands aren’t the same as R2. I reached out to Fujitsu USA (hhkeyboard.us, “Realforce R2 & R3 Keyboards with Topre Key Switches - HHKB”) for help after my Ctrl and Caps Lock somehow got switched. I got a weird reply saying that Fujitsu USA doesn’t sell R3 keyboards and so they could not help me. This seems like something that would have taken a single email to Fujitsu Japan by them could have resolved (I can’t for the life of me find an email for them myself!), but nothing. Really off-putting customer service.