For me, there are a lot of factors that go into determining whether or not I'll buy organic vs. conventional. In Canada a farm can be certified as organic because the farm grows organic products. However, since Canada is only 1 of 3 countries in the world that allows the use of GMOs (genetically modified organisms), the organic foods we grow are not truly organic in the strictest sense of the term. There is enough contamination in our soil, that if Canada outlawed GMOs it would take about 400 years for our soil to become decontaminated.
GMOs are so undesirable that our government offered produce at a dirt cheap price to a poor country in Africa (I'm sorry, I can't remember which one) and they refused to purchase the produce.
In a perfect world, none of the food I consume would have any chemicals in it, but we are making progress in how these chemicals affect our bodies. There are many chemicals being used nowadays that have a surprisingly short lifespan in our bodies. Some chemicals we consume due to conventional farming stay in the body 24 hours, even less, and is at such a low concentration as to have little or no effect on the body.
Now, it would take a bit or research on the individuals part, but if I had the option of buying truly organic asparagus from Bolivia, or buying conventional asparagus that has been exposed to a low toxic chemical grown locally, I'll opt for the local stuff. Because for me, I'm trying to find a balance between what's best for my health and what's best for the environment.
One thing I wouldn't budge on though is apples, I absolutely will not buy Canadian apples, they are one of the most horribly contaminated products you can get from our country.
Also, I can walk to my grocery store, buy my organic and conventioanl foods, and walk home in a half hour. If I were to buy only organic, I would have to go to 3 or 4 stores here in Toronto, only one store being in walking distance. I'm not willing to spend that amount of time getting groceries, plus, exactly how much crap am I pumping into the air because I now have to drive to get my food? Again, I'm trying to balance health and environment.