The best place to look is eBay, or another third party supplier. Simply, because it's cheaper. And usually, they are the same battery you'd buy from the manufacturer, just without the manufacturer's badge on it.
For example, I got a quote from Dell for a 9 cell battery for this laptop. $192AU. I got an IDENTICAL (other than it doesn't have a Dell badge on it) off eBay for $90AU (shipping included). Absolute bargain.