It’s not optical, and it’s not “fast” in any traditional sense of the word, but LTO tapes can kind of approach what you’re suggesting. I’ve seen LTO-7 tapes sell for as low as $10 on eBay sometimes, and they advertise that you can get upwards of 15TB of storage if you enable compression.

Granted, while the tapes are comparatively cheap, the tape drives very much are not…