Gasoline costs four bucks, but a gallon of it will get you twenty or thirty miles farther away from your mother-in-law, so it's worth it. Printer ink is famously expensive, going for upwards of $8000 a gallon, but at least you can use it to print a letter to the editor of your newspaper complaining about high gasoline prices. Lots of things are expensive, but we're hard pressed to come up with anything that seems to costs so much for how little you get than a text message. All the major carriers are raising their price for a single text message to an astonishing twenty cents. 140 bytes of data for twenty cents.
If the same pricing was applied on a per-byte basis to downloading one 4MB song it would cost the user almost $6,000 to download a single song via SMS texting.
One can easily assume that the mark-up on a text message is several thousands times what it actually costs carriers to transmit this little bit of data, considering that mobile operators are only charging $30 to $40 a month extra for mobile data plans that offer 5MB worth of data per month.
The reason that carriers are charging so much for text messages is because they can. Even at 15 cents and 20 cents a pop, people are willing to pay for it. The carriers are also trying to get consumers to sign up for text messaging packages and unlimited plans that vary in price from $5 a month extra for 200 messages to $20 a month extra for unlimited texting on AT&T's network, for example.
The RIAA actually wants to charge you $6000 per downloaded song, but that's a topic for another day. Why anyone would spend twenty cents to type OH HAI BFF SIT KTHXBAI when they have unlimited calling and an e-mail is free is one of the dark mysteries of the universe.