I was at my folks place when my stepfather said he needs a cannon. I said, "Your right, you do need a cannon. What for?" He's wanting an artillery piece that he'll likely never shoot but would like to know he could. Size counts. Used is OK. A barrel needing a carriage is OK. No particular historical period is specified, but it should look cool. He doesn't have plans on declaring war on the next county, but that could change over time. In short, he's flexable about what he gets and doesn't have a budget staked out yet. He just needs a cannon.
I looked at a few sights from the sources sticky. Lots to digest and I'm not done looking through there.
All that in mind, what do thos of you who know more about this that I do (that's a big group) reccomend for a cannon to be had just because?