Oh gosh, it's been forever since I got him, but I just bought them directly from Sidney and scratched every card I got. It didn't seem to take too long before I got him.
The nice things about Fairground Scratchcards are that you can buy more in a shorter amount of time, and they seem to have a higher likelihood of winning than the Lost Desert cards(I do LD cards now, and don't even bother to scratch the Scorched Treasure or Coltzan's Cash ones). The NP difference seemed pretty negligible after a while.
"Oh, better far to live and die/Under the brave black flag I fly/Than play a sanctimonious part/With a pirate head and a pirate heart."