Craig Brown says Norwich City's promotion to England's top-flight will make it more difficult for left-back Steven Smith to return to Aberdeen.
Brown, who confirmed a trial for former West Ham striker Daniel Uchechi, had hoped Smith would be back at Pittodrie after his successful loan spell.
"I think it'll be quite difficult to get anyone whose - the rumour is that - wages double," said the Dons manager.
"So quite clearly it will be harder to move him now than it was a year ago."
The Dons had hoped that Norwich's promotion from the Championship would make Smith less likely to be in manager Paul Lambert's plans.
But Brown told his club website: "I think the money might make it quite difficult for us."
The Dons boss is seeking another striker with Scotland international Chris Maguire widely expected to join Derby County should the two clubs agree a compensation package.
Brown said "we are happy with the four strikers that we have" but that "we could do with another striker" because it might not be enough depth for the whole season.
"But if someone offers us Lionel Messi or some very good striker in addition to that then we will have a look and see if he is any use to us," the manager told his club website.
The 21-year-old Uchechi will be given the chance to impress in pre-season training.
He began his career with Charlton Athletic before joining West Ham in 2009 but moved to his homeland with Dender before returning to the UK on loan to Leicester City last term.
"We had a request from an agent about Danny and he told me what a wonderful player he was," Brown said of the Nigeria Under-20 international who has yet to become a first-team regular with a British club.
"We will have a look at him and he seems to be a reasonably good player."
Aberdeen's only signing so far this summer is 31-year-old former Preston and Derby defender Youl Mawene, who was a free agent after leaving Greek club Panserraikos, and Brown had heard that it had not excited some Dons fans.
"It's more important that they are excited after they see him play a few games, that would please me even more, but I'm very confident about the ability of Mawene," said the manager.
"But we're not going to sign players for the sake of it.
"I've watched other clubs make a lot of signings and I'm not envious of any of them.
"I wouldn't like the supporters to think we are not on the case as we are all working diligently on improving the team."