The force said that the scam involved a vehicle, usually a van, being advertised on an online shopping platform.
Buyers would contact the seller and then deposit cash into a bank account after agreeing to purchase the vehicle.
However, upon trying to pick the van up they would be sent to a random address occupied by a person who had nothing to do with the advert.
Officers said a number of bank accounts were used for the victims to transfer the deposit money to.
As part of their investigation, police found the accounts belonged to about 90 different people who had let the criminals use their bank accounts to move money after being manipulated or lured by an offer of payment.
Cumbor, of Tudor Road in Doncaster, Michael Stokes, of Oakmount Road in Eastleigh, Hampshire, and Patrick Stokes, of Rookes Crescent in Chelmsford, all pleaded guilty to conspiracy to defraud and conceal/disguise/convert/transfer/ remove criminal property.
Det Ch Insp Sedgwick said: “This was a dedicated and thorough investigation which uncovered a fraud conspiracy which was impacting victims on a national scale.”