Even if you're shopping at an organic or natural supermarket, you still need to pay attention to signage and prices. Just because an organic supermarket sells produce, this doesn't automatically mean all the produce offered is actually organic. And this non-organic produce could cost from 30 to 50 percent more than it would if you bought it at a regular supermarket.
The reason for this price differential is likely because of produce seasonality. If certain produce is out of season in the area, the store may pay extra to ship in non-organic produce to keep you shopping there. Just make sure you keep an eye on prices, and as a general rule, stick to seasonal fruits and vegetables that you know came from local sources.