Honestly, prices in the United States for some items seem very high, at least to me. I have full confidence in your calculations. Here's the equivalent cost from Germany:
Feta: 1.89 Red Onion: 0.5 Red bell pepper: 0.7 Green bell pepper 0.7 Chicken thigh: 2.8 Cucumber: 0.79 Tiny tomatoes: 0.99 Olive oil: 0.3 Lemons: 0.69 Oregano: 0.1 Red wine vinegar: 0.1 (all values in Euro)
While Americans tend to earn higher wages, this really illustrates why ppp calculations matter.