You can order those parts from Brownells.
You may have tried to order the trigger kit that costs >$100. You can order this one:
http://www.brownells.com/rifle-parts/triggers-bottom-metals/performance-upgrade-kits/ruger-10-22-hammer-sear-package-prod9864.aspx
It's only $61.99 so there's no problem having it shipped up to Canada. I only needed the hammer, so I ordered
http://www.brownells.com/rifle-parts/triggers-bottom-metals/hammer-parts/hammers/10-22-drop-in-hammer-prod13872.aspx.
They sent it to me no problem.
next time i wont call..guess the last guy i talked to had no clue...got my kit its on the way 72.50 all in! to whoever wanted to sell there old hammer n sear stock for 100... thisis why i said thats expensive