There are two options for transit. The first is public transit, but this is not available in all areas. The second is an automobile. This is the more expensive option. If public transit is available to you, I would implore you to strongly consider it as an option for you. While this solution is not perfect, it is the best all around option.
I implore you, if you do not live in a county that offers proper public transit, I would suggest that you move to a county that does offer public transportation. This is because public transit is truly an affordable solution for your limited income.
What I Do
I use public transit most of the time. I also have a transit card which allows me to have a 3 hour pass every time I pay for my ride. In my instance, I budget $1.40/ride. More about this option will be on the bus page of this section.