The club's supporters stumped up the cash for a one-page message in an Italian newspaper bidding farewell to their former boss in response to his original effort
In response, fans created the 'Grazie Mancini fund' which raised £7,000, enabling them to return the gesture in the Italian daily newspaper.
The idea was the brainchild of City supporter Adam Keyworth, who also insisted that any money left over will be donated to a local charity for disabled children.
"We raised £5,000 in the first two days and the money has just continued to pour in," he told BBC Sport.
"We didn’t get a chance to say goodbye to Mancini as the sacking was quite messy so we’re hoping, now we have the money, to put the ad in this weekend.
"I’m told Mancini is aware of the plan. After his advert last week we thought, what better way to say thank you to him?"