The Hammers were desperately unlucky to be held to a 1-1 draw by the Red Devils on Sunday after Dimitri Payet's sumptuous late free-kick looked to have given Slaven Bilic's men a deserved place in the semi-finals at Wembley.
But Anthony Martial bundled home a scrappy equaliser to set up a fitting last ever FA Cup game at West Ham's Boleyn Ground home of 112 years ahead of their big move to the Olympic Stadium this summer.
More than 9,000 West Ham fans made their way to Manchester and at times you would have been forgiven for thinking it was a home match such was the vociferousness of their support.
Bilic and his players clearly appreciated the fans' efforts and applauded their fervent support on the pitch at Old Trafford afterwards.
But it also didn't go unnoticed in the board room either.
Fitting gesture for a fitting fixture
And now speaking in his latest column on West Ham's official website, Hammers co-owner Sullivan has made a pledge to ensure the replay is affordable for everyone as a reward to his club's 'magnificent' fans.
"Our 9,000 supporters who went up to Manchester were magnificent and it could have been 20,000 if we could have got the tickets," Sullivan told whufc.com.
"We will be pricing the replay at home far cheaper than the away game even though its the quarter-final of the cup.
"It was disappointing that we could not hold onto the lead, but there is still everything to play for and it promises to be another special night under the lights.
"It will be the last ever cup tie to be played at the Boleyn Ground and I know our fans will make it an evening to remember."
The date for the replay has not been set and will depend largely on the fate of Louis van Gaal's side in the Europa League this Thursday as they trail Liverpool 2-0 from the first leg of their last 16 tie.
The outcome of that game will then dictate when the replay can be arranged for.