You may try contacting some local computer shops to see if they can get one fairly cheap from a used out dated device.
Unless you know someone who has a similar lifebook to yours that no longer works, your not going to get away with not having to pay something for it.
I would suggest you try using e-bay as a good source in locating a cheap keyboard replacement for your device.
The keyboards are really not that hard to replace since they are located on the external side of the computer, there is usually only one modular ribbon wire that connects the main board to this section and the screws are usually hidden under a hole plug, which is removed with a flat screw driver. These are usually near where the screen hinges are attached to the bottom section.
Hope this information helps you.