This is a plush set of Yuki and Kyo in their animal versions released by the actual magazine that the manga ran in, Hana to Yume. I don't remember how I came upon owning these, but here they are.
Many times things like these were send-away items where you had to get tickets out of one or more issues of the magazine, and send in the tickets/coupons with money for the postage and/or item itself. These in particular I did not acquire myself this way, I'm not sure Hana to Yume allowed other countries to participate outside of Japan like Ribon Magazine did.
For pricing, I've seen Kyo go for $30-45, I'm not sure about Yuki.
Edit: Kyo SOLD, Yuki SOLD