The Netherlands international was the Reds' top defensive target for the summer, being tipped to make a move to Anfield for a fee of between £50m and £60m.
Liverpool's illegal approach forced them to withdraw their interest and issue a public apology to the Saints earlier this month, but they continue to be linked with a move for the 25-year-old.
Nicol, who spent 13 years at Anfield during his playing days, believes that the asking price for Van Dijk is simply too much for Liverpool to pay, and is unsure whether he would make the desired impact on Merseyside.
Asked if a transfer could still be on the cards, he told ESPN: "If the price is right, then yes. If the price is right, which I hope is not £60m, because I don't think he's worth £60m.
"Liverpool need a centre-back, I guess sometimes you have to do what you have to do. Whether the valuation is correct or not, Liverpool need a centre-back.
"He is a good player, the question is can he deliver at Liverpool? He did it at Southampton, can he do it at one of the big boys? I don't know."
Southampton are refusing to sell any of their key players during the summer window, even if a big offer is tabled.