I've thought of the term "selective", but this seems to suggest that he/she picks his/her products carefully.
Instead, I'd like to place emphasis on the fact that he/she buys only a certain type of products from this store.
I've thought of the term "selective", but this seems to suggest that he/she picks his/her products carefully.
Instead, I'd like to place emphasis on the fact that he/she buys only a certain type of products from this store.
I think "brand-conscious" or "brand-loyal" might be it. (Using brand to indicate the particular retailer, not necessarily the product which may not carry a noticeable brand.)
The shopper could be "habitual" to further imply they are regular and predictable in their purchases.
adjective
of the nature of a habit; fixed by or resulting from habit: habitual courtesy.
being such by habit: a habitual gossip.
commonly used, followed, observed, etc., as by a particular person; customary: She took her habitual place at the table.
I'd like to place emphasis on the fact that he/she buys only a certain type of products from this store.
She is product-selective when she shops there
or
She is product-directed when she shops there
EDIT
I originally included the following possibilty
She is product-biased when she shops there
However user405662 comments "selectiveness need not imply bias."
I could appeal to the following definition
the fact of preferring a particular subject or thing:
She showed a scientific bias at an early age.
... but the primary definition of bias usually refers to "unfair" preference. What unfairness signifies with regard to shopping is debatable, but I will concede the point.
What about "single-item shopper" or using the item in question as the descriptor/adjective?
"Apple-seeking shopper hits pay dirt at Bob's Market."
"Apple-seeker finds missing ingredient at Bob's Market."
"Apples-only shopper, Mrs. Smith, pleased by Bob's bushels of Braeburns."
Sounds goofy, I guess.
You could also say something like, "Shopper on an apple mission/quest/search, Mrs. Smith, found what she needed at Bob's Market." It doesn't necessarily mean that she didn't buy anything else, but it's pretty clear that she did find the one item she wanted: apples.