I have those Descente Covers(and were cheaper on PBK, now out of stock). They are nice, I used them yesterday for 3 hours at 35 degrees, but I wouldn't use them in the rain and expect not to get wet. They aren't even designed to be waterproof... they are neoprene.

Speaking of PBK, every other week it seems they have a deal on shoe covers(not always waterproof). This week.