Or mix your own stash of sprinkles into a white cake mix.
I made most of my cupcakes in mini, using these supplies:
Mini champagne glasses. I found these at the thrift store...donated from a wedding, but I've also seen them at the Dollar Tree, and every craft store in the wedding favor section. They are much more affordable when feeding a crowd than trying to find large champagne glasses for a large crowd of people.
I used a whipped, vanilla icing on the cupcakes to hold on the champagne bubbles.
For the Bubbles: Wilton sells these white round 'bubble's in mass, or they have jars of sprinkles that are white and round. I think the most affordable (and tasty) way to add bubbles are white Sixlets. I've found them at a bunch of Candy Stores (after purchasing these Wilton candies for my trial run). They also have vanilla whoppers you can grab if you want a variety of bubble sizes.
I did make a few larger cupcakes, just to test out which idea I'd fall more deeply in love with.
These would be really fun to serve at midnight along with a fun toast, but I have to tell you, I think I'm going with a tower of the mini cupcakes with confetti scattered around the base. Mini always wins my heart.