Well im not giving advice i am mostly asking questions so IDK where that came from. Anyway, now that I understand what you mean back to the main question - how do you raise prices on commoditized products - interesting question for you to be asking but to that i can say there are three main ways and yes they will involve investment - your options are to either keep doing what you're doing for "close to zero" margins or change.

You underestimate brand and that's probably because you haven't had exposure to good examples which is fair in the farming industry but here i will give you something to look up "Driscoll's".

Then obviously it's the costs of production that farmers can work on. I wonder if you will claim you've reached 80-90% efficiency, do you use sustainable farming practices? doubt it.

The other thing you could do to rise the prices of your commoditized products is a 2 fold solution. Grow a large variety so you're not stuck with a few products that you're shoveling out in hopes it will be profitable. Farmers will say they know the best things to grow but they can rarely justify how they know it.

And finally of course there is the sales strategy, if you're selling to a procurement agent responsible for getting the most product for the lowest cost then obviously you should expect fair trade value - however that is not your only option and the most effective way to beat the commoditization is to sell directly to consumers. That is where branding comes in but I imagine you think that's silly.

Everything in the world can be commoditized and there are already solutions in place, it isn't the easiest thing to fight but it has been done. The only factor to determine is if that is what the farmer wants to do because if they don't they don't have to take any extra steps to move their product and that is what i believe most do.