You can buy and sell copper through online marketplaces. Online auction websites such as eBay are popular choices for buying and selling both copper jewelry and bullion. The company even dedicates a page specifically to the sale of copper bullion, according to its website.
Online auction sites can be hotbeds of available copper bullion for sale by both private parties and certified bullion and metal resellers. New listings become available each day for a variety of both certified and uncertified copper coins, bars and ingots at various price points and purity levels. Much of the bullion sold by authorized sellers contains certificates of both purity and authenticity, as explained by eBay's bullion page.
Copper, along with gold, silver, platinum and palladium, is frequently traded and invested as one might invest in the stock market. Each of these metals has a listing of current trading value on Nasdaq's commodity market page, and as of early 2015, the average price for a pound of copper fluctuates between $2.52 and $3.35.
Copper bullion is sold in a variety of weights, conditions and designs, and is available in coins, bars, and ingots, as stated by Provident Metals' knowledge center. Copper coins generally weigh one ounce apiece, and are minted at 99.99 percent purity.