Reliable way to determine value of old coins?

Hi, I've been running a penny drive for Free The Children, and while counting the pennies I raised I found several very old Canadian pennies, each in excellent condition. They range from 1920 to 1935, each made BEFORE Queen Elizabeth the firts. I'm not sure if this is the man's name, but around the edge it says "GEORGIVS V DEI GRA: REX ET IND: IMP: I looked at a few sites, one said they'd be worth anywhere between $0.85 and $10. Are there any sites where I can get a solid statement, or any traders that I can contact? If it makes any difference, I live in Canada. If these pennies are worth anything, how easy would it be to sell them? My penny drive ends at the end of December, and if I can get anything from these coins, I'd like to do it quickly so I can convert their worth into more pennies for the drive. Thanks!