How do you get a PSP battery

At you're local Best Buy, Wal mart, Game stop or Game Crazy. If you need absolutely need
one right now and can't get to a store. For the battery pack:

http://www.bestbuy.com/site/olspage.jsp?skuId=9328694&st=psp+battery&lp=1&type=product&cp=1&id=1218085898135

For AC Adapter Wall Plug-in:

http://www.bestbuy.com/site/olspage.jsp?skuId=7045805&st=psp+battery&lp=2&type=product&cp=1&id=1099397015047