There are a few factors to take into consideration here:
They're very hard to find, so, considering it as a limited item, you're justified in asking a reasonable price.
However, they're not as well remembered as the Nosy Bears. I think most people were never aware the Bunnies were produced.
A lot of people obviously, we know, want to collect the toys they remember from childhood, and, although there may be a lot of people who would like one, they don't have the sentiment attached to up their price range.
So, aside from that, it's down to the diehard fans to be willing to pay a higher price.
I don't know how hardcore the Nosy Bear fanbase is. As far as I'm aware, they're pretty big in France, and they seem to have a degree of popularity in Japan. If you auction, you may want to be open to international offers.
They don't often come up for sale, so there's not really a basis for comparison. I probably wouldn't let it go for less than $25, though, if the right people wanted it, that could just be a starting bid.
I recently picked up the green Nosy Bunny, Ducky, for $5, and I know that was a steal
