what kind of battery for my macbook 13 white mid 2007?

You can buy from the Apple Store > Rechargeable Battery - 13-inch MacBook (White) - Apple Store

You can get a new third party battery fairly cheap on eBay. Every MacBook from 2006 through Mid 2009 except the Late 2008 Aluminum Unibody and the Late 2009 and 2010 White Unibodies use the same A1185 battery.

White Batteries http://shop.ebay.com/i.html?_nkw=macbook+white+battery&_sacat=0&LH_BIN=1&_sop=12 &_dmpt=Laptop_Batteries&_odkw=macbook+black+battery&_osacat=0&_trksid=p3286.c0. m 270.l1313

Or for $129 from The Apple Store http://store.apple.com/us/product/MA566LL/A?mco=MTY3ODQ5OTY