Manchester City, Arsenal and Tottenham are all reported to have sent scouts to watch Dunk in Brighton's game at Millwall on Tuesday.
Poyet is aware of the interest but has warned the 19-year-old will not leave the Amex Stadium on the cheap.
"They will have to pay. Everybody has got a price and Dunky has got a price, because he is in the team and because of the way he is playing," he said.
"Sometimes you can't keep players forever. If that happens and he is going to play in the Premier League that is something I cannot control."