The former forward is concerned that big clubs will come in for their star players this summer.
The Saints endured a tough summer transfer window last year, selling off their stars from the previous season, with Adam Lallana, Dejan Lovren and Rickie Lambert joining Liverpool, and Luke Shaw heading to Manchester United.
Many had tipped them for relegation following those sales, but instead they have been highly impressive under new manager Ronald Koeman and look set to qualify for the Europa League.
Owen, though, believes retaining the services of their star turns could become a tough task for the second successive year.
“They’ve got some real good players in their team, “ he said.
“But you still fear that if there’s a top player, you think ‘one of the big boys is going to pinch him off you’.”
Regardless of that, though, it has been a highly impressive season from the Saints, with their 6-1 win over Aston Villa on Saturday afternoon another top performance in a campaign of many highlights.
At one point they had looked to be challenging for a Champions League place, such was the level of their performances, but the Saints have fallen away since then to end up in the Europa League mix instead.
And while the club is looking upwards and at a potential challenge for the top four in the future, Owen believes that is an unrealistic target for them at present.
“They’ve established themselves,” he added.
“It’s a great club and they’ve got some great players but they’re just not structured for it, they haven’t got the money for starters to qualify for the Champions League.”