I found this battery on ebay and I'm wondering if anyone here had tried it.
New 3000mA Extended Battery+Cover For Sprint HTC EVO 4G - eBay (item 180532669327 end time Aug-12-10 08:42:50 PDT)
New 3000mA Extended Battery+Cover For Sprint HTC EVO 4G - eBay (item 180532669327 end time Aug-12-10 08:42:50 PDT)