Chelsea have been linked with a move for Turkey international Tuncay, while Tottenham may come in for England midfielder Stewart Downing, and Wigan are maintaining a long-held interest in Egypt frontman Mido.
Southgate neither wants, nor has to sell any of his better players, but acknowledges he will have to if he wants to raise funds for his own winter spending plans.
He knows the valuations his club place on each of their employees and if an offer is too good to turn down, Boro could be prepared to do business.
However, Southgate is adamant that any potential purchaser will have to fight to prise any key men from his grasp.
Asked if he is preparing a contingency plan in case a substantial offer materialises, Southgate said: "In some respects, yes, but we are not here just for other football clubs to walk over.
"If people think they can just take our players out, then they are wrong. We are not here to help other clubs. No-one is going to try to help us.
"People seem to think they can unsettle our players or just waltz in and take them on a whim – well, they are going to find out that's not the case.
"We want as much stability as we can and if people do have an interest in our players, they need to get on with it.
"They need to make their ideas known to us so we can either say, 'Thank you very much, there you go', or 'No, nothing's going to happen', and they can move on with their lives."
Southgate has also warned any club preparing an offer not to bide their time hoping for a bargain buy late in the window.
He said: "I keep hearing rumour of what's going to come, but as yet we have had nothing, so I assume then it is not coming.
"Obviously, the longer time goes on, the less likely you are to want to part with people because you can't get people in to replace them."
That is exactly the situation which transpired during the summer of last year when Boxing Day opponents Everton ended weeks of speculation by tabling an £11.25 million offer for striker Yakubu.
The Nigeria international eventually completed his move to Goodison Park on Aug 30, leaving Boro no time in which to recruit a replacement, and Southgate is in no mood to find himself in a similar situation once again.
He said: "That's something you want to try to avoid. We are consistent as a club on our stance on that.
"But if people think we are a soft touch and just here to help everybody else, we know it's a cut-throat industry and we will be more than fighting our corner."
Meanwhile, Southgate has defended midfielder Julio Arca over the tackle on Fulham's Andy Johnson which many felt should have earned him a red card, the fate which befell Arsenal's Emmanuel Adebayor against Liverpool on Sunday.
He said: "I don't think there's any intent in either of them. But when you look at the pictures and you slow them down, they don't look good, so I can understand people's reaction to that.
"But I know the nature of our player and Julio isn't a malicious type at all. He wouldn't have wanted to cause any harm, that's for certain."
Meanwhile, Luke Moore believes he can deliver goals to help West Bromwich Albion's attempt at another 'great escape' if he is given an extended first-team run by manager Tony Mowbray.
Moore has endured a frustrating time since moving on loan from Aston Villa during the January transfer window before completing a £3.5 million move in the summer.
He has made only a handful of starts, with the likes of Kevin Phillips – now at Birmingham – Ishmael Miller and Roman Bednar all forcing their way ahead of him in the pecking order.
But Miller's cruciate ligament injury has handed Moore a reprieve and he showed cool finishing when netting his first goal for West Brom in Sunday's 2-1 home win over Manchester City.
Now he is looking to build on that breakthrough and help Albion emulate the feat of four years ago when they became the first side to be bottom of the Premier League at Christmas and escape relegation.
Moore said: "It's always a boost to score and as a striker I think I can kick on from here now.
"It's difficult when you're not in the team and you can't get a run going.
"I haven't had a consecutive run of games since I was back at Villa and it takes time.
"Any player who wants to play will speak to the manager. I'm not content to be here and just pick up my money. I want to play.
"There is no big issue with it but every player in my position would have a word with the manager. You just have to do it in the right way and I did it a long time ago.
"I feel good and hopefully I can kick on. I can score goals if I am starting games. I have always known that and I am sure the Villa fans know that.
"The last year has been frustrating but that's football. There are ups and downs and I have been around long enough to realise that. As a striker I need games. If I start games I can only get better."
Moore added: "I can't say my confidence wasn't affected because I am a striker and any striker would be lying if he said that. Your confidence does get affected but you have to have inner belief.
"One thing I am is an honest player and I work as hard as I can for as long as I can. But being out of the team is tough and you lose match fitness. When I am in the team my work-rate is high and I'm not ready to do that for 90 minutes yet."
Mowbray is looking for Albion to build on their first win in 11 games, although they face a daunting trip to Chelsea on Boxing Day.
He said: "We are never as bad as people make out when we don't win games and have competed in virtually every game we have played in the Premier League this season.
"We know we are a decent team, we aren't a bad team in this league and let's hope the Manchester City game is the first of a run where we can put some results together."