I mentioned before that I've supported indie polish developers. I have bought a few black and white topcoats, and I've also tried to make my own with black and white glitter that I've purchase online. I cheated with my own: I added black and white glitter to a bottle of Wet n Wild #469, and it looks and applies quite nicely. Here it is compared to other brands I've bought:
Mine is on the far right. But also pictured are: Lac Attack Ocelotta Spots, Cover Band Sticks and Stones, and my favorite of the three, one called Black Tie Affair. Two were purchased from Etsy; Sticks and Stones was bought from someone on eBay.
You can never have too much black and white polish!