I'm not sure if this will apply to all auto part stores or not, but the local auto part stores in my area (NJ) that carry Sylvania Silverstars have them on sale. The twin pack of SS go for $36.99, and the singles go for $19.99. But if you purchase a single bulb, you get the second for half price! So basically I picked up two 9005 SS for like $30! So you save about $7 by buying them separately instead of the twin pack.