The Belgian does not believe his 32 million euro fee will dwell on his mind and insists he was happy to wait until deadline day to seal his 'dream' move to Old Trafford.
David Moyes had attempted to bolster his midfield with moves for Thiago, Cesc Fabregas and Ander Herrera over the summer, but when those approaches proved unsuccessful he opted to sign the Belgium international he brought to Everton in 2008.
The Premier League champions' procrastination saw them pay far in excess of a buy-out clause in Fellaini's contract that expired at the end of July, but the 25-year-old has shrugged off criticism of the transfer fee.
"It's not my problem [the transfer fee]. No matter whether it is 20 million pounds, 25 million pounds, 30 million pounds, expensive or not, the players respect the players," he told reporters at a press conference.
"I need to work hard for my place because there are a lot of good players. I keep focused and I want to help the team and I will do everything for this," he added. "It is up to the manager but I want to play offensive midfield and help the team going forward, but the most important for me and the team is to win games."
Fellaini enjoyed five seasons at Everton under Moyes before following the Scot to Old Trafford on the final day of the window but acknowledged he had often thought the deal would never go through.
"With Everton, with the chairman you never know. Sometimes I thought no chance for me to join Manchester United. But in the end I was so happy because the chairman accepted the deal," the Belgian continued. "I talked with the manager [Roberto Martinez] as it is a big opportunity for me to join one of the biggest clubs in the world.
"He knew my objective: I want to win a trophy. I play football for this, so with Manchester United I have a chance to win something. Of course [there were nerves about the deal not being completed] because it's a chance to join Manchester United, but in the end for me it is a dream."