Bought the Ugreen Silicone Case for Apple AirPods from Lazada for S$4.15 during Lazada mid-year festival sale. The usual retail price is S$5.19. Shipping to Singapore is free on their Saver delivery option where it will take 13 to 16 days to reach you.
As the name of the product suggests, the case is made from silicone, and there are three colors to choose from, red, black, and dark blue. I picked black.