Best place to purchase new battery for X60s in the UK?

[CyberDude]

My battery in my X60s has just died after 4.5 years. I guess I cannot complain but now need to find a replacement. I was shocked to see that they go for £130 - £160 on Lenovo's site.

Can anyone recommend reputable suppliers in the UK for genuine OEM replacement batteries rather than 3rd party. I've looked through ebay but don't trust what's being listed. I don't know if I can believe some of the on-line shops google throws up either and don't want to buy a dud so would appreciate some guidance. The battery needs to function as the original, i.e. report it's voltage, capacity correctly and allow for the charging thresholds to be configured.

Thanks