The most affordable and efficient way to buy larger quantities of silver for investment purposes is to purchase bullion bars.  These bars do not have any collectible value, so their price is dependent on the current silver price.  Additionally, production costs for these bars are lower than for coins.

Because these products are bought and sold based on their weight and do not carry additional intrinsic value, they are often used for short term trading strategies.  

Silver bars are available in many sizes, but the most popular are 1 ounce, 5 ounces, 10 ounces, one kilogram and 100 ounces.

These bullion bars may be produced at both government and private mints. Popular producers are the Royal Canadian Mint, the Sunshine Mint (from Idaho) and Swiss producer, PAMP Suisse. 

Government-minted bars are usually more trusted, so they are easier to sell.  If you purchase privately produced bars, be sure to buy from a well-recognized brand.  Other brands may seem like a bargain, but if the name is not known and trusted by investors, you may have to sell for less. 

As a precious metal as well as a critical industrial material, investing in silver bars can be an efficient way to diversify your portfolio.  Overall, these bars are easy to transport and store. Usually, they can be readily sold as well.