Sir Alex Ferguson has put together a list of potential summer transfer targets as he tries to fill the void created by the imminent $130 million transfer of Cristiano Ronaldo to Real Madrid and the prospect of Carlos Tevez following Ronaldo out of Old Trafford. Manchester United’s first response will be to follow up its interest in Ecuadoran Luis Antonio Valencia and offer around $28 million to Wigan Athletic. Ferguson also admires Karim Benzema and will investigate the cost of signing the France striker from Lyon, particularly if Tevez goes through with his threat to leave. Jean Michel Aulas, the Lyon president, has stated that Benzema will not leave for less than $112 million, though many believe the French club would actually sell for half that amount. United is also monitoring Franck Ribery‘s availability, although the Bayern Munich player would prefer to move to Spain. Along with Valencia striker David Villa, Ribery is another target for Madrid in what is shaping up to be the most remarkable period of transfer spending in history.