Currently my laptop won't run on its battery. Or rather, it'll only run for 5 minutes without any mains. That's pretty poor and shows my battery is dead (it is over a year old, which is roughly the right lifespan).

Today I bought a new battery. It cost roughly £34 but I was pretty amazed at the distribution of costs for my little laptop battery. Mine was the cheapest I found for my HP NC4000 but others were around £60 in total. Just goes to show you; when buying laptop batteries it pays to shop around.