How much spending money for kids?

Hi all! We will be taking our two boys to Disney next year, they will be 9 and 3. I’m trying to give them gift cards throughout the year for Easter, Christmas, birthdays, etc as part of their gifts so that they have their spending money. Would $150 for each boy be enough for the trip? This is just for souvenirs, not for food or other expenses. We would be there 6 days. Thanks in advance!