I had thought that the SS-R10s had not been made for several years (produced from early-mid 90s); a quick search shows that it's still on the SONY website of current models here
but a different search within the Sony website shows that they are no longer selling them. They were/are a custom-order-only pair of speakers and as far as I know, only sold in Japan.
I expect the only way you would be able to find them is through HiFiDo
or a similar source for used components. I saw a pair for sale a few months ago elsewhere (in Japan) but did not have a chance to go in and they disappeared in a few days. I can't remember what they were offered for but a reasonable guess of approximate range of used prices if and when a pair comes back on the market would be between JPY 800,000 and 1.2mil (roughly US$7,000-11,000 (there is no real blue book on custom-made products)).
The only two comments I have heard about them were that 1) they were great, and 2) that the bass was lacking. #2 is not difficult to understand as the specs suggest they go down to 35Hz. The other possibility is that they weren't driven well - they are only 80dB sensitive so I imagine they need a lot of power to drive adequately.