I buy mostly local and/or organic.

With animal products I care about the organic label. Knowing my food is free of added hormones is important to me, as is knowing the animals providing it have access to the outdoors. With grocery items, the organic label is more of a shortcut than something I care about directly -- those items labeled organic are more likely to have a simple ingredients list with real food items, which I prefer over long lists of mostly preservatives and chemical shortcuts.

You do have to stay on top of greenwashing (and out-and-out fraud), but to me the value is worth it.

As for cost, I've noticed, at least in our region, that while conventional food costs have risen dramatically lately, my grocery bill has not. The organic foods that come from the farmer's market actually cost less at this point than conventional foods at the grocery store, and organic grocery items are comparable or only very slightly higher. Using coupons available at the local co-op and shopping sales for those things not available locally, I usually spend less for organic grocery items than conventional ones, even on those things that cost more.

What I don't believe is that one should feel morally superior for shopping organic or inferior for not. I shop that way because it makes sense for me, is easily available, and while we're not well off -- cooking is a hobby, so buying premium ingredients and spending less on entertainment and eating out than others might is a happy trade off.