I have a 04 Malibu Lt with over 130,000 wont Start?..

So I have this old car. Was my grannys it has
been in two wrecks that i know of front
ditches. But lately the battery wont start the
car, i can hear the crank and it doesnt start.
now i have gotten charges and it has started
it back up but, it seems like everytime the
car gets shut off now I need to jump it. I was
going to get a battery i know its 3 years old
but car shared with 3 adults. or someone
told me starter....im on foxed income please
help which should i get to fix problem?...