Hey there Megan,
Welcome to planDisney and thank you for your question. I can certainly relate to regretting not picking up an item I had been eyeing on a trip to the Happiest Place on Earth - I've definitely been there as well.
Unfortunately, if you're not able to find it on
Disneystore.com then the item is likely exclusive merchandise for the Disneyland Resort. There are always a good number of magical finds you'll see at the parks (and only at the parks) on your trips, so it's always a good idea to snag them if you can when you're there! Additionally, if you don't plan to go in the parks, but are able to get back in the area, you can also usually have pretty good luck checking
World of Disney in the Downtown Disney District.
In the meantime, you could keep an eye on Disneystore.com to see if it does become available at some point down the road - that does sometimes happen. Additionally, I suppose it gives you another reason to start planning your next trip!
Sorry I didn't have better news for you, Megan! Here's hoping that the item appears on Disneystore.com eventually or that it gives you enough reason for another trip back to the Happiest Place on Earth.
Have a Magical Day,
Greg