No, it is not in fact. Scandinavian att köpa (å kjøpe) come from Germanic kaup which is often believed to come from Latin caupo (shopkeeper). Kupować and kupić come however from Proto-Slavic "kupovati" and "kupiti".
But in fact there are many Scandinavian words which sound very similar to Polish words because of their common Germanic etymology. As I master Norwegian much better than Swedish, I will write them in Norwegian, I'm pretty sure you'll get the point. For example: paret/para (the pair), rådet/rada (the council), å småke/smakować (to taste, to try, to taste good), å male/malować (to paint) etc.
I hope this' gonna cheer you up :-)