[vath2001]

I would recommend going to AutoZone for a battery... and save about $100.

Before changing the battery, starting pulling fuses. My car had the horn stuck (steering wheel air bag) and both horns are bad, so I didn't know it (never tested the horns when I bought the car). When I pull the air bag out, I heard a "click", push in "click". So my relay was held closed by the horn, causing the battery to drain.

I would also have a shop check to see what the alternator is putting out. Is a simple check to verify that the battery is being charged. I would do that first, before changing batteries.