I'm sure you could buy an S4 with extended warranty, and still be WELL within your budget.
As for reliability, well...it's a relatively new car. And any German car will have its issues after 50-100k miles. I'm just trying to be helpful. If you want something bulletproof, then look no further than Toyota. I'm sure you can find a Toyota camry that will easily do 400-500k miles without a hitch.