They are adorable, aren't they!? I love K.S. novelty bags.
They do go on sale, quite regularly in fact. I couldn't tell you the dates of sales because I don't shop K.S. often, but I know they have surprise sales on the website, as well as regular seasonal sales. Your best bet is either to tag the bag on Shoptagr and get a notification when the price drops, or to check the website regularly for or a surprise sale/ preferred customer event.
I will also add that many of the novelty bags are functional ones. I own an Owl bag that is a WOC and is big enough to function as a daily bag. I've also seen Parrot, Whale, Dog and Porcupine shaped bags that were all large enough to carry a lot, so if you're looking for a novelty bag that isn't so small that it's only decorative, then you can always wait it out for the next collection because each collection seems to have at least one animal shaped bag (although chances of getting your favourite colour again would be low).
HTH