average cost vs monetary value

average cost and monetary value both are nouns.

Word	Noun	Adjective	Verb	Adverb
average cost	Yes	No	No	No
monetary value	Yes	No	No	No

As nouns, monetary value is a hypernym of average cost; that is, monetary value is a word with a broader meaning than average cost:

average cost: total cost for all units bought (or produced) divided by the number of units
monetary value: the property of having material worth (often indicated by the amount of money something would bring if sold)

Other hypernyms of average cost include cost, price.

average cost (noun)	monetary value (noun)
total cost for all units bought (or produced) divided by the number of units	the property of having material worth (often indicated by the amount of money something would bring if sold)