if you're going into special shops and buying special things, like posh veggieburgers and organic beans, they're probably made in smaller factories with higher production costs, from better quality ingredients and materials, with better treated staff, etc. it costs more money to make these things, so it costs more for you to buy them too.
basic things (like big bags of beans, rice, potatoes, veggies, bulk dried soya mince) that you can use to make your own food from scratch, really are very cheap. especially if you buy them from stores where lots of people people buy them really often and get through a lot of them. buying your chinese veggies for stirfry from a chinese supermarket, your indian spices and rice for curry from a shop where indian people get theirs, etc, will save you lots of money.
i don't buy a lot of expensive stuff. i make my own food, and treat special things as treats.
what foods specifically are you talking about? can you give examples?