I have a mid-2009 MBP Unibody (MacBookPro5,5, MB990LL/A) that could use a new battery as it looses about 15-20% of a full charge in sleep mode over 8 hours...and will be completely depleted in about 2 - 3 hours of use. It does have a samsung 830 SSD in it with a fresh install of ML, but other than that its bone stock still working well. That said I know Apple will replace the battery for $130. I don't mind paying this but for something this simple the Apple Store is a bit out of my way to make it worth it (1 hour car ride each way). So I've seen many places selling a battery to replace mine with, but how do I know what to buy - search by Apple Part number? Are ebay batteries OK? I know some will say this is why you pay the $130 to Apple - which I'll do if I'm not confident I'm buying the right thing. Any help is greatly appreciated.