Best bargain out there would be doing it yourself in the comfort of your own garage. Although, it may require some work and tools (ramps, oil pan, oil filter wrench, 14mm open end wrench) it will save you money in the long run and you'll be sure the job was done right. Finding 0w-20 is like sifting through dirt for gold out here in SD but the I usually call in before I head out to Napa and usually run about $5-6/qt.

So in all I spend about ~$40 (4qts, oil filter,fuel injector cleaner)

Don't forget to recycle your oil afterwards