The Canadian mint has been producing Proof-like Sets of coins since 1953. These are not actual proof coins, but they are high-quality strikes from normal 'business' dies. They are packaged in cellophane and sold with a small collector premium. Some have grown valuable over the years, especially the early dates. The list below shows typical values for the hot sets:
1953: $760 US dollars
1961 to 1967: $35
After 1967 Canadian 'silver' coins were made out of nickel, although a few special dates contain silver (see this CoinQuest page). For sets with pre-1968 coins, silver content runs like this:
DOLLAR: 0.600 troy ounces silver
50 CENTS: 0.300 ounces
25 CENTS: 0.150 ounces
10 CENTS: 0.060 ounces
Multiply the current price of silver (see kitco.com) by the ounce measures to determine the value of these coins.
1967 was the centennial of Canada's confederation, an Pieter asked about this specific year. It was standard practice that year for enterprising people to buy proof-like sets in cellophane and re-package them in fancy 'Canada Centennial' holders. These look nice, but the packaging does not add value to the coins.
However, the mint issued a special Black Box proof-like set which contained a $20 gold coin. This set is worth a lot of money due to gold content. The 1967 $20 gold coin contains 0.528 troy ounces of gold. Click to kitco.com to find the current gold price and multiply. That will be the value of a 1967 Black Box set.