The price for a white, king size down comforter varies, especially based on thread count. But expect anywhere from about $40 to $200 for the higher thread count options. Prices on overstock.com can vary widely depending on not only what is in stock, but also the desired quality level of the comforter. Typically, a king size down comforter will come in under $100 with the lowest price one currently at $42.99 and the highest at $202.99.