It's not archaic, at least not in mainland China.Hi Kirstin,
The word you are looking for is 犯贱 [犯賤]。
Note that 犯贱 is a verb, you can't use it as an adjective. Eg. 那人真犯贱。
There exist a term 贱人 which is literally "cheap person", but it's archaic and is more accurately translate as "worthless being".
pianyi is used to mean "the price of something that can be bought is low".I think "cheap" can be understood, even if it is not an "official" word. In one occasion I misspoke with someone, I was going to say "piaoliang" and somehow the word "pianyi" came to my mouth.... needless to say, I was in very very deep trouble. Believe me, it DOES have that meaning.