Isn't it against company policy to have and use personal dash cameras in any company vehicle?
I'm not 100% sure on that. Will check.
As far as finding one, they are all over the place, cheap. Just know, you'll want one with significant run time, loop feature' or something similar. Also, you'll want 12 volt power cord, NOT batteries.
Quick search turned up the following lists:
Amazon.com: dash cam - Car Electronics / Car & Vehicle Electronics: Electronics
dash cam - Newegg.com