Holiday Light Necklace/Bulbs

During December Six Flags and a lot of other theme parks sell necklaces of full sized battery-powered C9 (I think they're C9s) lights that flash as souvenirs for their holiday festivities (I say holiday because not everyone celebrates Christmas: The corporate holiday that includes awkward dinners and gift openings with family members and follows Black Eye Friday and Hallow(een)/Empty Wallet Day). I asked the vendor how much they were: $12!!! I think I'll save those $12 and use what I have at hom