Any sort of luxury item costs exorbitant amounts. Evie's sweet habit is probably more expensive than some drug habits. - any real chocolate costs a ton.

Most convenience stores will sell sweets, candy, and synthetic chocolate, but real chocolate (not that I'd call M&M's the realest chocolate) costs a whole lot. 

Any real luxury item, chocolate, coffee, tobacco, etc costs a lot, and likely had a synthetic substitute for poorer folk.