The Latics had a bid of £3million turned down by the Eagles for the highly-rated winger in the summer, and may need to double their offer to secure the youngster
Martinez offered £3million for Zaha during the transfer window, but the bid was turned down by Palace, with the club reportedly wanting double that figure for the England Under-21 star.
The Latics continue to look for a replacement for Victor Moses, after he was allowed to make the move to Chelsea this summer.
"I think Wilfried has tremendous potential. He has grown massively over the last 12 months," Martinez told reporters.
"The first time we saw him was against us in the League Cup a year ago, but he has come on a lot since then.
"Crystal Palace have high thoughts of him. I don’t think it is going to be a realistic player for us. In these situations it has to be value for money."
Martinez also confirmed his interest in Honduras international Roger Espinoza, who is currently under contract at MLS side Kansas City until the end of the year.
Espinoza, who starred for his country at this summer's Olympics, still requires further caps for Honduras to qualify for a work permit.
"We will keep a close eye on him," Martinez added.
"We have got really strong links with Honduras and been very successful there with Wilson Palacios, Hendry Thomas and Maynor Figueroa."