United will reportedly pay more to sign Maguire from Leicester, and Spector thinks the Red Devils are not getting the best possible deal.
"I was actually a bit surprised by [the Maguire approach]. I think he's a very good central defender and he has proven himself at the international level as well, but a part of me thought that they would go abroad to fill that role," said Spector.
"I thought they would potentially be chasing someone like De Ligt but Maguire is a good player and I think he could be good for the club, but only for the right price.
"It seems like English players command a premium and if they could get him for the right price, I think it would be a good buy."