Lukaku has impressed during his season-long loan from Chelsea and marked his return from a month out of action by scoring the winner against West Ham United at the weekend.
Veteran midfielder Gareth Barry, who is on loan from Manchester City, and Barcelona winger Gerard Deulofeu have also caught the eye at Goodison Park this term.
Martinez would be keen to hang on to his temporary players, but is prepared to use the loan market again next season if the likes of Lukaku and Deulofeu move on.
"All I want for the boys that we have on loan is that they have an incredible experience as players," said Martinez.
"Some of the young ones just to develop, Gareth just to have a real enjoyment and create memories for the future.
"The loan market is very important for us. If we can keep those players great, if not then we will have to use the loan market again."
Lukaku has scored 10 goals in 20 league appearances for Everton and Martinez feels the Belgium striker has a similar influence for the club as Lionel Messi has for Barcelona.
The Everton boss added: "Lukaku is an irreplaceable footballer and that is a reality. Barcelona are one of the best teams in the world but when they have not got Messi, the team suffers."
Leighton Baines created Lukaku's goal against West Ham and Martinez is expecting big things from the England international now that the left-back's future has been resolved.
"It's been a difficult season for him because of the transfer speculation," said Martinez.
"He has had a little interruption but I think Leighton can have a phenomenal end to the campaign."