The Red Knights consortium has said it will not pay over the odds for Man Utd in the present economic climate.
The group of wealthy businessmen is believed to value the club at no more than £1bn.
They now say talks with potential investors "have reinforced our belief it is wrong to offer above fair value".
A spokesman for the Glazer family which owns the club, reiterated that United, valued at £1.2bn by US business magazine Forbes, was not for sale.
The recent Forbes report on football clubs also stated that increasing sponsorship and media revenue meant "the news continues to be good for investors".
However, in its new statement the Red Knights say they believe that the value of Manchester United will be reduced over time "given headwinds facing the game of football".
The Red Knights also say they are still trying to assemble a group of wealthy investors necessary to buy the club.
"This statement is meant to show that the Red Knights will not over-pay for United, nor will they be rushed," said BBC sports news correspondent Dan Roan.
"They believe one billion is the true value for the club. But the Glazers regard it as nothing more than the latest round of a battle for publicity, and are again stressing they have no intention to sell."
Their numbers so far also include Jim O'Neill, chief economist at Goldman Sachs, and lawyer Mark Rawlinson, and it has recruited the Japanese investment bank Nomura to help it put together a bid.
Manchester United was bought by the Glazer family for £800m in 2005. At the weekend the club finished second to Chelsea in the Premier League.
They were also knocked out of the Champions League in the quarter finals, and have ended the season relatively unsuccessfully by their standards, winning only the League Cup.
On Sunday, Manchester United supporters unhappy at the Glazers' regime set off a smoke bomb outside Old Trafford.
Critics say the family has saddled United with massive debts, and the Red Knights has said that one of the priorities is to reduce debt levels.
In the latest accounts, to July 2009, debts at the club's parent company Red Football Joint Venture increased to £716.5m.
Fans have launched a campaign to oust the Glazers, many boycotting the traditional red shirts and scarves and instead wearing green and gold, the original colours of Newton Heath, the amateur side which was founded in 1878 and became Manchester United.
"Our primary goals remain to facilitate a return of ownership of the club to its supporters and the community; and to restore the financial health of the club," said a statement from the Red Knights.
However, they said this process would take time.