The three men and a woman were arrested when several vehicles were stopped by Gardaí in Drogheda, Co Louth, yesterday.
Subsequently, the Gardaí searched several locations in Louth, Meath, Dublin and Wexford. It was during these searches that they found the cash and drugs, including cocaine.
The Gardaí also took six watches and some electronic devices.
The three arrested are being questioned at a Garda station in Dublin.