If that's the case it's more likely someone at PrimeCables made a mistake since they advertised it for $39.99. So quite likely they had a price error, a bunch sold at the wrong price, then they realized it and corrected it to $39.99. In any case, that's a good buy at $29.99.
UPDATE: My mistake! It was YESTERDAY'S deal of the day for $39.99, not today.