costly vs pricey

costly and pricey both are adjectives.

Word	Noun	Adjective	Verb	Adverb
costly	No	Yes	No	No
pricey	No	Yes	No	No

As adjectives, costly and pricey are synonyms defined as:

Other synonyms of costly include dear, high-priced, pricy.

costly (adjective)	pricey (adjective)
having a high price	having a high price
entailing great loss or sacrifice