Mo Bangura has completed his loan spell at the club who sold him to the Hoops for £2.2million 18 months ago.
The Sierra Leone hitman picked up where he left off with the Stockholm side, and rediscovered the goal touch which deserted him when he arrived at Parkhead.
Now, AIK – whose season has ended – want to make the transfer permanent, but Celtic are not about to write off their outlay, and manager Neil Lennon has made it clear the Swedes will have to start talking serious money – or else Bangura will be rejoining his team-mates at Parkhead.
The Hoops boss said: "Mo's loan is now up. They (AIK) will have to make an offer for him, or he will be coming back here."
However, AIK sports director, Jens Andersson, admits Bangura might be out of their price range.
When asked how much Celtic are looking to recoup, he said: "I don't want to say how much, but it's way too much for us. We can't afford the adventure with big investment for an individual."
Lennon gave Bangura – who is under contract until 2015 – every opportunity to claim a first-team place at Celtic.
But the 23-year-old's failure to find the target in 16 appearances, a succession of injuries, and the striking form of men like Gary Hooper and Anthony Stokes, plus the emergence of Tony Watt and the arrival of Miku and Lassad Nouioui, squeezed him out.
Lennon wanted Bangura to get more game time, so sanctioned the loan deal at the end of August.
At AIK, he scored five goals in 15 appearances – including a winner against PSV in the Europa League – to help rebuild his confidence and assist the club to a fourth-place finish in the championship.
AIK want him to stay, but fear wages and Celtic's asking price might make this difficult.
If they can cut a deal, it would add even more to the pot which Lennon can use to further strengthen his squad in the January window, with a central defender and a wide left player with pace top of the wish list.
"We've been looking at players for the last two or three months, and I'm hoping to add to the squad," added Lennon. "If we can't, so be it."
The Hoops boss does not envisage major surgery, and is already keenly anticipating the fitness of long-term injured attackers, James Forrest – who resumes full training on Monday – and Stokes, who is about a month away from playing again following an ankle injury.
But he is willing to make additions if he believes the right player at the right price becomes available.
Celtic face another five games before the window opens, starting tonight at Arbroath, and the SPL have been criticised for not helping them fly the flag for Scotland by re-arranging games before the last 16 ties of the Champions League in February and March.
But Lennon has no complaints and said: "We've never asked for it (help), so I don't know where the story is coming from. It would put the SPL in a very difficult position because they have been criticised for not helping teams in the past. I'd not expect that to happen to us, and we will deal with it."
By then, Lennon hopes to have Hooper's name on a new contract, though the talks with his representatives planned for last weekend have been delayed for a week.
Hooper has had a virus, but is expected to play at Arbroath, though Joe Ledley and Kris Commons will both be missing for up to 10 days.