The centre, set up by the Government to help opted-out schools, is in the throes of launching a company to break into the Pounds 250 million-a-year schools and colleges information technology market.
The venture could bring in nearly Pounds 500,000 from schools alone within the next two years and will give companies a "direct route into a named and known market" as well as guaranteeing space at an annual conference.
The centre, which lost its Government grant this April, is setting up an off-shoot company to begin trading next year. The Government now funds the Grant Maintained Schools Foundation, which provides information to schools seeking to opt out. This year the foundation received a Pounds 690,000 grant from the Department for Education for the service. In previous years, the centre received Pounds 2 million in Government money. Both the centre and the foundation are chaired by Sir Robert Balchin.
The centre is aiming to provide an information technology subscription scheme for the UK's 8,000 state and independent secondary schools - for a flat rate fee of Pounds 165 a year.
Company membership, with links into schools, will also be available at Pounds 6,000 and Pounds 10,000.
Adrian Pritchard, director of the GMSC, said in a letter to companies that the scheme would "provide a direct route to the market" and "act as a focal point for information and market intelligence as well as providing a source of potential leads".
He told The TES that the company would not be selling on the names of schools to computer firms, but that it would be a "matching service". David Blunkett, Labour's education spokesman, said: "It is ironic that such a stalwart of the GM movement has had to recognise that schools cannot exist in isolation, and when he needs a new market he must turn to all secondary schools in the country rather than one small group."
Mr Pritchard plans to have 2,400 members within two years and to retain nine out of 10 members year on year. In his letter, he told companies: "It is not generally known that the nation's schools and colleges spend some Pounds 250 million per year on information technology."
He said schools would be able to purchase equipment and software at the best rate available as well as receiving the latest IT information from his "one-stop shop".
For Pounds 165 per annum, Mr Pritchard promised schools would receive regular information bulletins, special offers, a help desk and the opportunity to attend an IT-dedicated annual conference.
Companies could take out either a premium membership of Pounds 10,000 whose benefits would include regular contributions to bulletins, opportunities to market-test new and planned developments, and guaranteed space at the annual conference or a standard membership for Pounds 6,000 , to include contributions to the bulletins where space permitted, and an invitation to take part in the conference.
Mr Pritchard told The TES: "When we kissed goodbye to government funding we didn't have to concern ourselves with the things that we have had to traditionally concern ourselves with."
The centre is also aiming to publish books for local authority and public schools next year on administration, finance and purchasing.
Martin Rogers, from Local Schools Information, said: "If anyone was trying to set up a business dependent on the secondary sector they would be foolish to restrict themselves to a small and no longer expanding GM part of it."