As a coin buyer for gold I have bought coins from regular people looking to sell and not just from the coin stores. Fakes are always a concern in the back of my head when buying from non-dealer individuals. I have purchased this item called a fisch coin tester and used it every time I make a transaction.
They come available in various "wallets", with the "wallet" allowing you to test coins from that country. For instance, if I am buying American Gold Eagles Wallet #2 would allow me to test any of the sizes that they have in addition to the Krugerrands etc. Since the Gold Maple Leafs are different you would have to buy a separate wallet for that. The more "wallets" you buy the cheaper it gets.
The person that I have dealt with when purchasing these items was very friendly and answered any questions quickly. Here is the website below for those interested in checking it out.