When you go look at the car, check the oil and see if it's milky, or black, or if there's even any in it. You will definitely need a new battery, unless the seller has replaced it. Make sure to see if there were any animals living in it.
The gas is going to be bad. It's going to need a lot of TLC. However if the price is right, you can budget money for the parts to get it back to a good runner. Good luck!