Tyler's correct miles. Buying unshelled nuts is the only guarantee.
I will kindly supply you with my own 'secret' local supplier who I used to buy from regularly (I don't personally eat nuts anymore). I believe it's now possible to shop via their website. The most exciting thing is - their nuts are affordable and they have huge supplies! They're a parrot specialist in Norfolk but, after lengthy discussions with the owner, I discovered that the nuts sold as 'parrot food' are, in fact, graded fit for human consumption. Owners spend thousands on their exotic parrots and only want the best food for them. The nuts, actually, are no different to the tiny bags one pays a small fortune for in the health shops!! In fact, they're better because they're unshelled and not rancid like most you'd buy in the stores. Shhhh, don't tell anyone!!

They're not organic but, to be honest, I don't think this is an issue with unshelled nuts. They sell in bags as large as 25kg if I recall correctly and do some wonderful unusual and difficult to obtain nuts as well as the usual offerings.
You can find their website here:
http://www.junglegold.com/I hope that's helpful!

The only pain is, of course, one has to shell them all! It makes sense to buy a decent nutcracker for the job. I imported one called 'The Rocket' from the US which did a fine job and which I'd recommend. I used to shell, soak and dehydrate in bulk which makes much more sense if one is consuming any reasonable quantity.