Liverpool signed van Djk from Southampton for £75m on January 1 and Crooks feels the Reds should now move for Brighton defender Dunk, who he says can play for a top-four team.
Crooks named Dunk in his team of the festive period and has also picked the 26-year-old several times in his team of the week this season.
He said: "What a result it was for Brighton to take the points against Watford on 23 December. Connor Goldson - nine months after heart surgery - produced a performance that must have frightened the life out of the surgeon that did the operation. His quality on the ball was impressive, especially alongside the outstanding Dunk.
"It was Dunk's performance against Watford, and again at Newcastle, that left me thinking he is a top-four defender if ever I saw one. Whether he can mentally cope in that environment would be my only concern, but in terms of his defensive qualities I don't think I've seen a better centre-back this season. I've seen more polished performances but nothing quite so efficient.
"It struck me that Liverpool could do themselves a great service by making an audacious move for Dunk. What would he cost - £35m in today's grossly over-inflated market?
"Offer £45m and I've no doubt Brighton boss Chris Hughton would drive him to Anfield himself. Could Brighton afford to turn that down? Alongside Virgil van Dijk, Liverpool would suddenly have two towering defenders who know how to defend. They should be paying me a consultancy for this column!"
Crooks also named Albion keeper Mathew Ryan in his team of the festive period but still has doubts whether Brighton will stay up.
He said: "Ryan was outstanding during the 1-0 win over Watford and the 0-0 draw with Newcastle, helping provide four massive points for the Seagulls. I find Brighton deadly dull as an attacking force, but as a defensive unit they were magnificent against the Hornets and Magpies, and did not give Chelsea a sniff for 45 minutes on Boxing Day. They work hard as a team, are so brilliantly drilled, and give their manager everything.
"Ryan's performances have been so compelling he has left Tim Krul with very little chance to come in and prove himself. In the Newcastle game the stop from Isaac Hayden that took a massive deflection en route to goal was wonderful but the save from a flicked header from Dwight Gayle was even better.
"I've been saying all season that Brighton will run out of gas, and it seemed to be happening quicker than I thought against Bournemouth on New Year's Day. They must pick up maximum points at home against teams such as the Cherries otherwise their existence in the Premier League will be short-lived. However, neither of the two goals they conceded in the 2-2 draw were down to Ryan."
Crooks' team of the festive period was: Ryan; Walker, Dunk, Azpilicueta; Sterling, Fernandinho, Coutinho, Lingard; Salah, Kane, Sanchez.