Coutinho handed in a transfer request at Liverpool, who reportedly rebuffed three bids from Barca during the closing weeks of the window – the last of which was understood to have come in at $A202 million.
Barca director Albert Soler claimed Liverpool attempted to broker a $A304 million sale on deadline day, only for the Catalan giant to balk at the price.
Reports this week suggested Soler would step away from footballing duties at Camp Nou and, speaking at a news conference to announce Barcelona's latest financial results, Grau insisted a move for Brazil midfielder Coutinho was still on the agenda.
"We are ready for buying Coutinho in the winter market or any player the technical staff requests," he said.
"But it is important to adjust ourselves, so if there have to be arrivals there must be exits as well."
Grau announced Barcelona's income to have reached $A1.078 billion for the 2016-2017 season, with a record budget of $A1.36 billion in place for 2017-2018.
Neymar's world record departure to Paris Saint-Germain for $A331 million in August did much to swell the coffers and Grau outlined how Barca benefited from the windfall.
"We must forget about the price paid for Neymar last summer," he added.
"After taxes we received about €188m in income and a direct financial impact on the club's treasury of €144m."