sponsor vs buy at

sponsor is a noun but buy at is not a noun.

Word	Noun	Adjective	Verb	Adverb
sponsor	Yes	No	Yes	No
buy at	No	No	Yes	No

As verbs, sponsor and buy at are synonyms defined as:

sponsor and buy at: do one's shopping at; do business with; be a customer or client of

Other synonyms of sponsor include frequent, patronise, patronize, shop, shop at.

sponsor (noun)	buy at (noun)
someone who supports or champions something
an advocate who presents a person (as for an award or a degree or an introduction etc.)

sponsor (verb)	buy at (verb)
assume sponsorship of	do one's shopping at; do business with; be a customer or client of
assume responsibility for or leadership of
do one's shopping at; do business with; be a customer or client of