Middlesbrough boss Tony Mowbray has warned Swansea they will have to stump up the cash if they want Leroy Lita and Marvin Emnes.
The Welsh side have seen a £2million bid for the attacking pair rejected by Boro, but are anticipating a fresh offer from the Premier League new-boys.
Swansea's chief scout, David Leadbeater, was at the Northern Echo Arena on Saturday to watch the duo as Boro went down 4-2 to Darlington.
Another season in the Championship has forced Boro to reassess their finances, which has prompted the sales of Didier Digard, Andrew Taylor and Kris Boyd.
But Mowbray insists he will not allow his strikers to leave The Riverside without being properly remunerated for their services.
"In my own mind, I think if Swansea have got any real, genuine interest they should let us know," he told the Journal.
"Maybe that was why their chief scout was there - I don't know. Do they know enough about these players? I'd like to think that they do.
"What I would say is that the closer it gets to the start of the season, the less likely we are to want to let any of them go. There's no fire sale on."
Boro have always been backed in the transfer market by chairman Steve Gibson, who has done his best to ensure they remain competitive.
And he too is fully behind his manager and will not sell players for below their current market value.
Mowbray added: "The chairman has stated pretty clearly that if the deal doesn't suit our football club, there's no deal to be done.
"It's about getting a balance. We need to readjust the finances and as we do that, we'll take each proposed deal as it comes along and decide whether it is good for us or not good for us.
"At the moment, there are no deals for either of our strikers that is suitable for us."