Costco Salary. Costco average salary is $77,208, median salary is $76,043 with a salary range from $23,858 to $126,000. Costco salaries are collected from government agencies and companies.Each salary is associated with a real job position.Costco salary statistics is not exclusive and is for reference only.ostco average salary is $77,208, median salary is $76,043 with a salary range from $23,858 to $126,000. Costco salaries are collected from government agencies and companies. Each salary is associated with a real job position.