Quote from jakus12
No, parts on a laptop can only be replaced by the manufacturer or a VERY experienced computer techie. You'd have to contact them for a custom one. They'd probably charge you through the roof for it, though. That's even if they agree to do it, which they might not.
For a battery? No. They're available on pretty much any manufacturer's website, through ebay, online stores and even google offers battery-selling websites.
@TS, higher capacity batterys are reasonably easy to get, but they are quite expensive. I would prefer to get two six-cells than a six cell and a 12, but that being said I'm tight on cash at the moment. Obviously 6 & 12 is BETTER, but price-for-price maybe not.