Do you have a Disney Store near you? They may have sold out by now, but they had a couple of different Christmas antenna toppers. Otherwise, I would try Ebay.
I just bought two really cute ones at TDS last week. A snowman Mickey head, and a Gingerbread Mickey Head.
I don't put them on my car but have a great display of my Mickey antenna heads.
Check out your locl Disney Store. Peggie
We were there in June and forgot to get the Christmas balls. I went to TDS and found a sparkly green mickey it will have to do untill we can go back to the world in May. Just a thought maybe I should drive the kids to Down Town Dis this weekend to shop. Uh Oh, there goes another pay check.
We have antenna toppers of all kinds at Disney Days of Christmas at DTD. This includes the Santa Mickey (he has feet), NBC Santa Jack, MM with the antlers, Santa Stitch & the new topper that looks like an ornament. I bought this one for my car. The Happiest Celebration one needs to go!