I would expect supplements to always be more expensive than the equivalent amount of food-grade product. If it's not more expensive, I'd expect it to be food-grade spice jammed into a capsule. There's a lot of markup and marketing expense in the supplement business that you don't usually find on the food side.
In your shoes if looking for economy, I'd be thinking hard about the reasons why I'm buying organic, and whether (in the small gross quantities consumed) the risk from residual pesticides and such was worth paying so much premium to avoid. But I am much more about
including economic risk in my personal risk analyses than the average Permie seems to be.
The turmeric I use costs about fifty cents an ounce (dried/powdered) from the Asian supermarket. But it's mystery stuff from China. I pays me money and I takes me chances.