If you are in a shop you know, then you are aware of what you want from life, but if it is an unfamiliar shop, then you need to open your mind to new possibilities.
Shops and stores are places of interaction, whether this is the exchange of money and goods, or the communication between the salesperson and the shopper. In dreams, they therefore represent things you desire in life and the manner in which you go about getting these things. A supermarket, for instance, suggests a wide range of choices, a village store represents the essential things in life, whilst a store or website selling a range of odds and ends—such as an antiques store, an auction site on the Internet or even a car-boot sale—suggests the small details of everyday life that are often overlooked. Your dream may be urging you to pay attention to these.
If your dream was quite mundane and you saw yourself doing your weekly grocery shop, then your dreaming mind may simply have been processing a memory or reminding you that you need to go shopping. Alternatively, such a dream may be suggesting that you are taking good care of your basic emotional needs. If, however, you had a dream in which you could not decide what to buy, this may be referring to some kind of confusion or indecision in waking life.
If someone you know in your dream transformed into a sales assistant, your dreaming mind may have been commenting on the emotional cost of your relationship with them.
Bear in mind, too, that whilst stores, supermarkets and shopping malls are places of opportunity and choice, they also threaten potential exclusion and humiliation if you do not possess the necessary funds; your feelings about going on your dream shopping trip should indicate whether or not you are feeling empowered or denied in your waking life.
If you dream that a shop is closed or that you have insufficient money, this may indicate that you feel the things you want from life are unattainable. Your dream may be telling you to lower your expectations and set more realistic goals. Finally, if your idea of heaven is to go on an exclusive shopping trip and spend loads of cash in luxury stores, then a dream of having a day doing just that may be simple wish-fulfillment.