The phrase "a substantial sum in" is correct and usable in written English.
It can be used when referring to a significant amount of money or resources in a specific context, such as finance or transactions.
Example: "The company reported a substantial sum in profits this quarter, exceeding all expectations."
Alternatives: "a considerable amount in" or "a significant total in".
That is a substantial sum in the very poor communities where the campaign is often focused.
Associated Newspapers, publisher of the paper, had agreed to apologise and to pay a substantial sum in damages and costs.
This can add up to a substantial sum in penalties, in addition to dunning and a damaged credit rating.
By the end of his college days, at Pace University, he was making about two thousand dollars a month, a substantial sum in the late nineteen-sixties.
Soon he says he had amassed around $100,000, a substantial sum in a country where the average salary is less than $1,000 a year.
A metal manufacturer can supply molten metal to a nearby foundry and save it a substantial sum in transportation and remelting costs.
That is why Mark Shuttleworth also made the news this year in his attempt to get back a substantial sum (taken in levies) by suing those same authorities.
Betfair, the online betting exchange which pays Gray a substantial sum to appear in its advertising, said earlier in the day that, while it would not tolerate sexism, it had "no plans to change" its relationship with Gray.
McCain harvested more than 600,000 votes in this part of the state, and Romney has spent a substantial sum on advertising in Cleveland.
Sara Hernandez, a former aide to L.A. Councilman Jose Huizar, also raised a substantial sum, with $200,232 in contributions over the roughly two-week period after she jumped in the race.
For some, that privilege meant traveling long distances, spending a substantial sum or waiting in line for hours.
