THE design favoured by most people for the Brewery Yard development in Abergavenny will cost £2.5 million.
But Monmouthshire council has only set aside a budget of about £1 million for the preferred project.
Councillor Chris Woodhouse said one of the three proposals - which were all put forward by architects McGregor Smith - had been identified as the most popular following public meetings and workshops in schools.
But he admitted the council may not be able to fund the whole project.
Monmouthshire council regeneration officer Colin Phillips attended the Bryn Y Cwm area committee to present the design.
Key criteria for the plan include linkage between the redevelopment and the town, the market and parking facilities.
The preferred option would see Cibi stream become a feature of the site, glazed canopies with space for 74 stalls and the creation of four widened terraces.
Traffic in Cross Street is a key issue, and planning officers say that an alternative route into Market Street is needed.
Councillor Woodhouse said the town needed to be ambitious to make the regeneration work.
He said: "We must not look back in a few years and say we didn't go far enough."
But he warned: "There has to be a financial health warning. The council may not be able to provide all the funding for this preferred option."
Rick Longford, the council's economic development manager, said the costs were still a rough estimate.
"We hope to create it in the region of £2.5 million with about £1 million in funding from the authority, but they are initial estimates."
All three options were submitted by McGregor Smith, but as option three was clearly the most popular no costs were worked out for the others, Mr Longford said.
Councillor Jane Foulser has criticised the plan, and said there could be something more "beautiful" there, and something in keeping with an old-fashioned market.
A planning application for the scheme is due to be submitted to Monmouthshire council next month.
The council said because option three was preferred, the other two designs have not been costed.
Option one involved several elements, including a new civic space on Market Street which incorporates improved toilet facilities and framed artwork.
The second option is similar and includes two glazed canopies and viewing decks as well as the new civic space on market street.
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