Unfortunately that's the sad reality of collecting SMC, the tapes are very hard to find and if you do, they're very expensive.
The Sony M-9 Mono Microcassette Recorder, so much fun in red, I love how such a mundane product was still given the cool treatment. I'm not sure what "2B" is for? They don't show the gold model but I think that was a promotional version, maybe not for retail sale but purchased in large quanties for events.