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At 70 miles per hour, one can go 50 trillion miles in 81.5 million years. Assuming an average song length of 4 minutes, that much travel requires 10.7 trillion songs. The emusic Connoisseur plans allow one to buy 100 DRM-free songs for $25. At this price, enough music for a 50 trillion mile road trip would cost $2.68 trillion, or $320 billion less than Joseph Stiglitz and Linda Bilmes' estimate of $3 trillion for the total cost of the Iraq War.
Comic from XKCD, used with permission.