The best way to sell aluminum cans is at recycling centers, which melt down the aluminum and sell it. Cans also sometimes have a deposit value placed on them; if so, this value is paid in addition to the cost of the aluminum's value.
Despite being the most common metal in the earth's crust, aluminum is relatively expensive to refine but is easy to melt and reuse. As a result, it's profitable for companies to offer commercial aluminum recycling services. By paying people to bring in aluminum, these companies can operate without paying employees to bring cans in, although many have contracts with city or county governments.
In addition to the commercial value of aluminum, governments also sometimes offer benefits to recycling centers for processing aluminum. This further increases the value of recycled aluminum, which can result in better payouts to those who bring in aluminum cans. If possible, contact multiple centers to search for better rates; sellers with regular, large shipments might even be able to negotiate.
In many cases, companies actually offer more money for large deliveries of aluminum. Aluminum is relatively lightweight, so large amounts of it take up a significant amount of space. By offering incentives for those who deliver larger amounts, recycling centers are able to cut back on the labor required to prepare the aluminum for recycling.