The Goodison Park outfit have had Lukaku on loan from Chelsea this season, with the 20-year-old forward proving a huge hit by banging in 14 Premier League goals.
Everton want to make his move permanent at the end of the season and know that an impressive World Cup showing could push up his price. But Martinez insists he is not concerned about Lukaku's market value.
"I don't think that's my worry," the Spaniard told the Liverpool Echo. "The worry would be that if the deal was a cheap one, it would be because he has had a torrid time and hasn't fulfilled his potential.
"We are too close to Romelu to hope he has a poor tournament. We hope he has a really good World Cup and then decides to come to us.
"We'll see what's the best thing for everyone but everything will be in stages: how Chelsea are doing in their own squad and how that frees some players.
"It's going to take a bit of time and I don't think Romelu's situation is going to be resolved before the World Cup, in truth. I think it will be after the World Cup."