The Black Cats are understood to have tabled a bid for Norwich's Robbie Brady, reportedly in the region of Â£10million, although Moyes is not expecting any arrivals of that magnitude.
He said: "I'd be kidding you on if I said the players we are going to bring in in January are going to massively make a big difference because first of all, we probably couldn't get that level of player and secondly, we probably wouldn't have the finances to do that.
"To suggest that the player we bring in would be making a big difference, I think, wouldn't be correct."
Twelve months ago, then Sunderland boss Sam Allardyce swooped for Lamine Kone, Jan Kirchhoff and Wahbi Khazri and all three hit the ground running to inspire yet another great escape.
This time around, the landscape on Wearside is very different with successor Moyes describing the limited funds with which he has to play as "limited with a big 'L'".
Speculation surrounding Brady prompted hopes that there might be more leeway, although Moyes was giving nothing away.
Asked about the Republic of Ireland international, he said: "I wouldn't confirm or deny if I was in for any player
I can just tell you that we have been in for a few players and we are trying to see if we can bring things in."
However, Moyes also hinted that the club's targets are not the ones currently circulating on the rumour mill.
He said: "I'm sure there can be an element of truth in some of them, others there's none
Sometimes you play the game and you're telling everybody about transfers when there's not.
"I think we have been linked with about four of five players this week and I can tell you the players we're in for, it's been none of them."
Moyes, who also insisted there had been no fresh offers for either Jermain Defoe or Patrick van Aanholt and was unaware of any interest in Kone from Allardyce's Crystal Palace, will await developments off the pitch as he attempts to secure a first league win in five attempts at in-form West Brom on Saturday.
The Baggies currently sit in eighth place in the table with manager Tony Pulis having battled his way through a difficult start to his reign, a source of encouragement for his Black Cats counterpart.
He said: "Tony has done a good job wherever he has gone
Given time, he always puts together a good team, and he has done.
"You can see them beginning to build on what they have done and sometimes it takes a little bit of a while to appreciate how good a job he has done."
Source : PA