Mine are 10 weeks old & still haven't had scratch! I give them greens every day, BOSS, & sprouts. Once a week they get a bunch of hay. They also get a little wild bird seed once or twice a week. They get live meal worms about 3X a week. I don't think I'll even by scratch! One less thing to buy
Also depends on the climate and the type of scratch. I live in Georgia (hot most of the year) so I only give cracked corn or scratch in the cool/winter months. Giving corn as a treat in the summer when the birds are already struggling with the heat would make it worse for them.