So how crucial is organic, given the limited selection and cost?

To me it's very crucial. If you can envision a large circle that would be your digestive system, then over time fill that large circle with all the inorganic items you might eat. Hundreds, maybe thousands over the years of little circles within that large one.

It's not so much one inorganic item you eat, but what collectively they all contribute. Add to that any tap water with the chorine, flouride, thrown away medications, pesticides. All the toxins that you aborb through your skin from your bath, and shower water.

It might take some time, but eventually this mix of toxins that we are subject to every day can do damage.

Do what you can to avoid any of it that you can. You will be healthier.