Some tree trimming companies and utilities will deliver a load of woodchips and leaves to your home for no charge. There are several varieties to choose from. Cocoa bean shells have a delightful scent and a pleasing dark color. Pine is usually a lower cost option. Cedar and cypress tend to decompose slower than other organic mulches.
Some nurseries sell mulch by the truckload.
Prices vary according to the species of trees that grow in the area. Landscape professionals know what types of organic mulch are available locally. Many people like the look of inorganic mulch. It achieves many of the same results as organic mulch. Choices available include synthetic weed barrier, landscape fabric, and rock.