Only I have familiarity with is Bloomberg, if you have access. You can get historical prices and that sort of thing. Other sources must exist. HTH
This looks to be a good source for people who might have historical information on Bond, James: http://www.ajb007.co.uk/
try www.bradynet.com . not sure if it's got what you're after, but bonds are their game.. anyone for a 200% yielding argentina bond? lol