The Argentine striker has scored five goals in as many appearances after moving to the King Power Stadium from Brighton & Hove Albion for £8m during the summer.
Both Nugent and Ulloa got on the scoresheet in Leicester's 5-3 victory over Manchester United on Sunday.
"Leo has been a revelation so far," Nugent told ITV Sport.
"He has come in from Brighton and he has scored lots of goals. At £8m he has turned out to be a bargain."
Leicester currently sit seventh in the Premier League following the victory.