Note that for the newer cars you begin to run into a synthetic oil recomendation, in particular for cars with turbochargers (since that gets really hot and the oil has to lube the rotor). Anyway if the car needs synthetic oil then you are looking at $75 oil changes.
I just left Walmart and bought a 5 qt container of 0W20 Synthetic Mobil One for $24.95. The filter for my 4 cyl Camry is about 4 bucks so with tax it's about $30 to change the oil and filter.