Boneless, skinless chicken breast is about 740 calories per pound, and what, like $7 per pound? That's about 105 calories per dollar.
A pound of almonds is about 2600 calories and $10. That's 260 calories per dollar, or about 60% cheaper for the same calories.
Ground beef, 20% fat 80% lean, is about 1136 calories per pound. Say organic beef is also $7, then it's 162 calories per dollar. So almonds are 35% cheaper than beef.
Taken to the extreme, soybean oil has about 4000 calories per 16oz (not sure if fl oz of 1 lb. I will ignore the difference here). The commodity price of soybean oil (futures) is about 42 cents per pound, so about 9500 calories per dollar. It's almost 1/10 of the cost of organic boneless skinless chicken breast. Clearly, to minimize food cost you should buy soybean oil by the ton on the commodities market and eat nothing else. Your food spending will be $6.30 per month, or about $76 per year for a 2000 calorie per day diet. A metric ton of soybean oil will completely feed you for 14 years if you don't die of malnutrition first. Incredibly it's cheaper than diesel fuel (retail) since it's production is subsidized, it isn't taxed as fuel, and you are buying in bulk. This explains why soybean oil is so common in processed/industrial foods. Palm oil is even slightly cheaper and has the added benefit of destroying rainforests.
Apologies in advance if I made any math errors.
Back on topic, if you have a Vitamin Cottage Natural Grocers near you, they seem to have good quality nuts. They keep them refrigerated, which helps keep them fresh. I only buy the inorganic ones, though, because the organic ones are too expensive. It also may be the most hippie store I've ever been to, but if you bike there you'll fit right in.