In a survey conducted in July 2009, asking 1,000 adult consumers which of the many available accessories they acquired at the time the handset was purchased, it was found that the U.S. the average mobile phone owner spends roughly $60 on accessories over the life of their phone.

According to ABI Research (which conducted the, well, research), it's not just chargers, but all the other usual suspects as well:

"Chargers - car chargers, standard chargers and additional chargers - led the field in terms of numbers purchased."

"Carrying or protective cases were the next most popular, followed by batteries and memory cards. Other accessory types include hands-free kits, headsets, and cosmetic enhancements."

Via techcrunch: Wait, the cell phone accessory market is worth how much? and Webpronews.