You may not want to accept something completely unrelated to the field that interests you most. You may want to make sure the company is stable. You don't want to get caught in a massive downsizing soon after you are hired. You want to find a place where you'll be comfortable. If the job calls for expensive business suits, the polo shirts you wore at your last job will need to be replaced immediately.
Some employers offer an advance to pay for such prejob expenses.
This money also could be used toward relocation. Another promotion should be visible within the next few years. A company car, an expense account or a great dental policy could outweigh a seemingly low salary. Some companies will offer profit-sharing or 401K plans as well, which also could compensate for a lower wage. Some companies may offer more comprehensive health and insurance policies.