The absolute cheapest option is to make your own from unsweetened shredded coconut.
I soak one cup of shredded coconut in a cup of water for several hours, then blend, adding two more cups of water in the process. Pour through a strainer (or cloth, or whatever).
Adjust amounts of water based on your preference and brand of coconut. I find that this method makes something that works well for most uses, but it isn't nearly as thick as canned coconut milk (I'm not certain you can get it that thick at home without boiling to condense it), so I still use canned if I'm doing something that needs the thicker consistency (ice cream, etc), or if I get lazy.
The leftover pulp can be dried and ground further if desired (I use a food processor) to make coconut flour, to be even more frugal.
It's also additive-free, BPA-free, and you can use organic shredded coconut and still make it for cheaper than the cheapest canned coconut milk.
But if you're looking for canned coconut milk, Walmart's Golden Star brand tastes decent and has no additives (emulsifiers, preservatives, whiteners, flavoring), though I'm sure it's not organic and the cans are BPA-lined... but the same is true for all but the most expensive coconut milk.
coconut milk is just watered down coconut cream. i just buy the cream & water it down myself.
how much you water it down will depend on the cream you buy & personal preference.
the cans of cream i buy (which are the same price as the cans of milk in the same brand) are roughly 18% fat (18g/100ml).
& i turn one 400ml can of cream into 2 Litres of milk (equiv 5 x 400ml cans of milk), saving me the cost of 4 cans of milk. nice.
I live 1.5 hours from the nearest Whole Foods, but when I go, I stock up on their store brand cans. Organic, and I think a little over $1.50 a can.
UPDATE My local Wal Mart carries a brand called Golden Star- it's just coconut milk & water, tastes great, and is under $1.50!
I don't know where NC is; I'm assuming the USA so I can't comment specifics but in the UK I found the cheapest (and additive free) coconut milk in Asian stores, I guess try the same.
Oh, I think Trader Joes light is additive free too.
Or you could make your own. :-)
This is not the cheapest coconut milk available, but the best price I've found on organic coconut milk in BPA-free cans is through Azure Standard. You can check their website to see if there is a drop point near you.
If that's not an option or you don't care whether it is organic and/or BPA-free, Asian grocery stores usually have the best price.
Do you have a Trader Joes where you live? I buy mine there and the cans are only $1. I've made my own coconut milk in the past, but I really don't see the savings. Its cheaper both in cost and in time to just by TJ's cans.
aroy-d has an awesome coconut cream that has nothing but 100% coconut! and since it doesn't come in cans you don't have to worry about the whole BPA problem. it looks like you can buy a 33oz. carton it on amazon at http://www.amazon.com/Aroy-D-Coconut-Cream-100%25-Pure/dp/B0074A3WXG/ref=sr_1_1?s=grocery&ie=UTF8&qid=1332764971&sr=1-1. in my neighborhood, i can buy this at an indian grocer even cheaper for $4.99. if you have any ethnic grocers, it might be worth checking out!
Why does my coconut milk taste soapy? 4 Answers
Coconut Milk Beverages 6 Answers