Simon Grayson says Sunderland have to be patient to land their top transfer targets this month.
The Black Cats boss is eager to bring in more attacking firepower, with a centre-back also high on the agenda.
Talks have been ongoing with Aston Villa regarding striker Ross McCormack, but the 30-year-old's bumper wages mean negotiations are complex.
That reflects the wider picture in the market, as the Black Cats look to add quality to their squad but with deals that do not risk the club's already difficult financial situation.
Grayson said: "Certain players are on big contracts and their clubs are not going to loan them out or sell them to the first team that comes along – they might wait until later in the window because someone else might come in from another club.
"We've done the deals that we have done so far because it has been right for the clubs that we have got them from, but some of the deals we have been asking about are not quite right for other clubs at this moment in time.
"It's going to be a case of showing some patience, and not diving in when we don't need to," he added.
"There are players who have been offered to us over the last few days that have gone on to move to other clubs, but I felt that they weren't going to make us any better.
"We have a good base here in the squad but we do need the extra quality that we are going to bring in, and sometimes that has to wait until later in the window because the Premier League clubs are getting their squad sorted.
"That's really the market we are looking in – along with other Championship clubs – but when they get their players in, there will be a knock-on effect.
Grayson has also said that further outgoings are likely.
Jeremain Lens left for Besiktas at the weekend, with the Turkish club announcing on Monday that the deal includes a fee for a year-long loan, with an option to buy for around €4 million in the summer. Sources on Wearside are adamant that there is little chance of the Dutch winger returning next summer.
The Black Cats boss expects further disruption in the coming weeks but says the club are well placed to deal with any eventuality.
He said: "Jeremain was one of the people who made it clear early on that he didn't want to stay at the football club.
"What I told him from Day One is that he had to work hard, join in with what all the other players were doing, and he did that – you saw that in some of his performances in pre-season.
"But, ultimately, when we got the right bid we took it.
"I've got a meeting with Martin Bain this afternoon to see where we go now in terms of recruiting new players.
"When will I know my strongest team? Well it won’t be until the window shuts. I’m aware of that, as is every other manager, you know you could lose players. We’re ready for that, we’ve got a list of replacements for any position that we might need, not just the ones people have mentioned, it could be any player."