Today, one SD card is worth a million C64 floppies
I did some quick math based on a figure of 170KB storage capacity for those floppy disks (which is what Wikipedia said) and I got 170 GB. OK, so in a sense you're spot-on, because there's SDXC cards with similar capacities (128 GB). But 128 GB cards are almost $200 right now (or, at least, that's what Amazon is selling them for), and the Pandora only officially supports two SDHC cards, which can only go up to 32 GB officially for a maximum of 64 GB. With that in mind, a million floppies is a bit of a stretch, don't you think?
Actually the floppies have two sides, so you could fit twice as much. Then again, the Pandora also has 2 SD slots. Sure, big SD cards are expensive, but not as expensive as one million floppies
... I don't remember how expensive they were back then, now they cost about 1 dollar per floppy (if you can still find them), so even if you take a huge quantity discount into account, so you can bring it down to 10 cents per floppy, it would still be $100,000. Plus the cost of the containers to put them in - I don't know exactly how much the weight is of one floppy, but it's probably more than 10 grams, so a million floppies would be more than 10 metric tons, you cannot just put them on a big pile because they would get crushed under their own weight, so some kind of containers would be absolutely necessary, adding to the cost.
I guess at some point in the not-so-far-away future there will be 256 GB and 512 GB SD cards, and some of them will probably work with the Pandora, probably not at higher speeds than 16 MB / sec but still... (not bad if you compare with C64, which would get maybe 4 KB / sec)
So no, I don't think my original post was exaggerating at all
Of course, there is no way you would need that many floppies, since all C64 stuff that has ever existed probably fits on "only" 10,000 or so floppies, which would easily fit on a 4GB SD card. For example, I found an archive somewhere on the internet that essentially contains all C64 games (it has about 17,000 titles so I guess it is quite complete, many are small tape games and every floppy side has its own title so this is much less than 10,000 floppies), and the complete archive fits in a .zip file of about 524 MB.