What is the name of a person who likes high quality items, not necessarily the most expensive, but the best for the money perhaps.
I would say "Connoisseur" is close, in particular in the sense of Merriam-Webster's second definition
one who enjoys with discrimination and appreciation of subtleties.
"a connoisseur of fine wines"
If you are looking for a noun-phrase, I can come up with
- "a conscientious shopper",
- "an educated consumer",
- "a price-conscious shopper"
These are not specific for quality versus price. They can be used for those buyers who are concerned with environmental and labor issues too.