buy in vs commerce

buy in is not a noun while commerce is a noun.

Word	Noun	Adjective	Verb	Adverb
buy in	No	No	Yes	No
commerce	Yes	No	No	No

buy in (noun)	commerce (noun)
	transactions (sales and purchases) having the objective of supplying commodities (goods and services)
	social exchange, especially of opinions, attitudes, etc.

buy in (verb)	commerce (verb)
amass so as to keep for future use or sale or for a particular occasion or use