02 sensors

[shepv8]

Hi all,
did a search but found no info, so,
Im looking to change the 02 sensors on my 06 LX focus. It has 100,000kms on it and its been a bit rough for a while. Also is a bit grumbly at low revs. I changed the plugs a few thou kays ago and this definately improved it but I suspect changing the 02 sensors may fix it up a bit more. Has anyone else done their sensors and where did u get them from. Theres a stack of them on ebay but mostly for the older model focus, not from 05 onwards. Any tips or things to watch for
Cheers
Shep