He told aldermen Monday that the city could save time and at least $1 million. Storm said the investment group he represents would consider a purchase, lease or lease-purchase option.
The bank building could meet the city's perceived needs without major remodeling, he said.
Storm said construction of a new building could total at least $3 million.
"We estimate we would save you $1 million to $1.5 million over a new (building) or tearing it down," he told the council.
City leaders have determined that the current city hall no longer meets modern building codes and is inadequate for Vermillion's city staff.
After 17 months of work, an advisory committee recommended the city demolish its present city hall building and construct a new one in its place.
Relocating city hall in the bank building was the committee's second choice.
Alderman Mary Edelen questioned whether the city could do better by constructing its own facility.
"Why would we as a city go through you (Storm) as a private citizen to do the interior of the building, when we could build our own building and do it exactly as we want?" she asked.
"And if we go with you, and the proposal is referred, will you finance the campaign? And what if it fails?" she wondered.
Storm said his group would likely spend funds to campaign for passage of a referendum. "But I'm not saying we would spend the same dollars (as the city council) to try to get it through," he added.