Thanks ccg for the Newfoundland suggestion. I indeed saw it when I was checking ebay, though I wasn't sure its association with the "mainstream" Canadian 50 cents. Some coinage websites mentioned the 1908 AG-3 can go as low as $3, though in ebay it's roughly $15 each, which seems more reasonable... I do like the back design of this coin, reminds me of the Mucha flurry style.
By the way, I understand that that $1 is nicknamed "Loonie" and $2 is nicknamed "Toonie". Is there one for the 50 cents? Will "half dollar" make sense? Just wonder if there is a good story behind I can use.