You can buy and use any charger with following specs,
output- 5 volt, 1 amper
Many respectable vendors have chargers equal to specs, samsung, lg, htc, sony, hamma and more...


http://www.htcaccessories.com.au/TC_A250.aspx


http://www.expansys.com.au/mobile-ph...r-ac-adaptors/



P.S. I use htc charger and it works just fine with my Nokia N9