Yeah, that last item should've been niji no shizuku (2-hour Drop and Rainbow Drop).
I was thinking about that "goals" part again...
Since the joke is that this store is offering items from a different game for sale but also that you can't buy them because you don't have the right currency...
since Gold is being used as our "real" currency in this game, my first though would be to price these items in Gil,
but then I thought maybe, taking a bit of a liberty, pricing these items in rupees might not be a bad idea. I know it's a real Asian currency rather than a real European currency (like DQ is supposed to be set), so it's not a perfect substitute, but it does fit of course in being, again, a real currency (like Momotarou is supposed to be in Japan) and being well-known from a different game that did exist when this game was released.
Reminds me of the first time I played FF7 and I got to the Gold Saucer.
"oh, it's 5 GP to use the save point. I don't know why there's a toll on this save point, but whatever. ... um, why's the game telling me I don't have enough, I got a few grand. Sits around awhile confused. Oh... THIS game uses Gil as the currency and GP must be something else. Whereas GP was the currency in previous localizations.
And that's probably why I'd want to make the "wrong currency" thing more clear, I guess.