Moyes said: "We could continue to stick to the same path but I think things have changed. We used to think it was only the bigger boys who spent serious money, but Manchester City are going to spend and so are Newcastle, Aston Villa and Tottenham, not to mention Portsmouth.
"So now you may have to spend more just to keep ahead of the teams you're in front of, as well as the ones you're trying to catch. That is the challenge.
"We are maybe looking to sign some Champions League-type players but what do they want? The Champions League - and Champions League money.
"So we have to try to find a way to meet that challenge and I would like to be able to say that we can bring Champions League players to this club."