Alex Rodriguez’s nephew was kidnapped and held for ransom in a Midtown hotel Wednesday night when a deal over a $600,000 Lamborghini went south, police sources told The Post. The retired slugger’s nephew, Norberto Susini, 29, plays minor-league ball, but his side hustle is slinging high-priced cars. He met up with prospective buyers Lamin Vucetovic, 33, and Anthony Gilkes, 30, in Times Square on Wednesday evening and they drove him to the Marriott Marquis, but once they got there, Vucetovic tried to pump the brakes on the deal, sources say.