But do the costs really compare?
Comparing "stealing" vs "infringing" ( http://offtheshelf.nowis.com/index.cfm?ID=5 ): stealing = $100,000 fine vs infringing = $3,400,000 fine, with a year in prison for both.
Comparing music piracy to other crimes in Illinois ( http://gapersblock.com/mechanics/2009/08/17/seven-crimes-to-consider-befor/ ): stealing a CD is a fine of $2500 and a year in jail vs the nearly $2 million that Jammie Thomas was hit with.
Comparing pirating music to stealing a CD in Massachusetts ( http://bostinno.streetwise.co/2012/05/22/bu-student-fined-675000-for-pirating-music-6-crimes-that-will-cost-you-less/ ): first offense for stealing retail goods less than $100 is a fine of $250 maximum vs the $675,000 that Joel Tenenbaum was fined
So, while the numbers vary, none of the fines for stealing a physical CD come close to the fine for downloading the same CD. Of course, downloading music is different than stealing a physical CD since the person is not holding onto an object that would otherwise be sold to someone else.
Comparing copyright infringement not with stealing a CD, but with crimes where someone fails to pay the required amount: http://www.techdirt.com/articles/20120201/01172117619/how-does-penalty-content-theft-match-up-with-similar-crimes.shtml
How do the civil damages or penalties for the different types of such “theft” compare? Failure to pay expected money under a contract doesn’t trigger a penalty: contract law usually says that a party can recover the money she expected but not punitive damages or attorneys fees (unless parties have specifically bargained to pay attorneys fees for a breach). Failure to pay rent usually requires payment of rent to cure the default. Failure to put money in the parking meter prompts a ticket for $60. In New York City, failure to pay the $2.50 subway fare results in a maximum fine of $100. [...] If we take copyright law’s maximum-penalty-to-price ratio as applied to an illegal download, and apply that same penalty-to-price ratio to the New York subway, the maximum penalty for jumping that turnstile and avoiding the $2.50 fare would be $375,000 instead of $100.
(I am not so sure that those other crimes really are similar since with places of residence or parking spots you really are dealing with a limited supply.)