Barry could make £1m from a match against star-studded opposition.
But the 27-year-old midfielder may waive any personal gain.
He told the Express & Star, "Niall Quinn donated money to charity and if something else can be achieved through it that's helping different causes, then fine."
"If you're donating money to charity, it's a big step."
The England midfielder would be embarrassed to be seen to be making money out of his testimonial.
"Talk about a testimonial game is a bit of a sticky subject," he said.
"In terms of a testimonial meaning 10 years at a club I'm proud to have achieved that. Come May it will be 10 years and a great achievement for myself and the club.
"Just being around fans and reading different comments of how they see it, it's a well-spoken subject about whether players should get testimonials these days with the amount of money in the game."