There have been reports in Spain claiming Messi could reunite with Pep Guardiola in Manchester after informing the Catalan giants he wants to leave.
While there aren't many teams who could fit the bill for Messi's wages, Mills believes the Premier League giants could use cash from shirt sales for the Argentine superstar.
"I don't think money is the huge issue in this," Mills told talkSPORT.
"I've just done a quick tally - in 2016, he sold two million shirts that year. Let's say you're making £40 profit on that shirt, that's £80m, that's £1.5m a week. That's his wages covered.
"He's only got a year left on his contract, so even if you have to pay £200m, the shirt sales alone probably cover his wages for every year that he's there, and then a bit more.
"I don't think money is an issue, it's whether he wants to leave Barcelona and come to Manchester."