My 15" MacBook Pro 5.1 (late 2008) battery is inflating to the point of nearly breaking the unibody battery cover, so I'm really into replacing it as soon as possible. There are loads of these batteries on eBay (mostly UK sellers with high reputation) that cost less than half of the price I'd have to pay for a battery on a local Apple reseller store.
My question is: is it safe to purchase batteries for MacBook Pros on eBay? Are there any known issues or ripoffs that I should know of?