White models are sold via retailers; black modems are sold/provided from ISPs.
Its best to find a white one unless buying from Cox as the white ones have a 1yr warranty through the manufacturer; the black ones are warrantied by Cox when purchased through them.
I bought an SB6182 from Cox last year - they had a promo that if you brought in batteries for recycling, you got $20 off networking equipment sold in the Cox store. The modem qualified.
