All US visas allowing work in the United States require you to have a US employer sponsor you for a specific job. Many US employers are willing to sponsor non-American citizens for work visas; however, on many occasions, your prospective employer may not be familiar with the E-3 visa category as it is only available for Australian citizens. Other visa categories are usually more expensive or extremely backlogged, so, if your prospective employer is turned-off by sponsoring you for a visa, make sure to mention the E-3 visa.