reliable laptop battery vendors?

[sethg-Dp9fwfP21SfQT0dZR+AlfA at public.gmane.org (Seth Gordon)]

My employer recently gave away some hardware it didn?t need any more, 
and I helped myself to a free ThinkPad T43.  The only problem with the 
machine is that the battery is non-functional; I can leave it plugged in 
all night, but as soon as the power cord is bumped, the screen goes black.

Googling ?t43 replacement battery? turns up a bunch of hits, all from 
vendors I?ve never heard of.  Who can I trust?