Proto-IE: *perk-, *merk-
Meaning: to buy
Latin: merx, -cis f. `Ware', mercārī `Handel treiben, kaufen', mercēs, -ēdis f. `Verdienst, Sold, Zins'
Other Italic: Osk amiricatud `*immercātō (ohne Entgelt)', amiricum `*immercārī'
Celtic: *hrknā- > OIr inf. dat. reicc `zu ferkaufen'
Russ. meaning: покупать
References: WP II 40 f (different in Pok.)