I do cut pictures from books.
Many of the books are children's workbooks. They often have the best pictures. Especially if you are looking for pictures for a phonics game, grab a phonics workbook. I save pages from the children's workbooks when they have good pictures on them. I have taught the children to be careful of writing on the pictures. Even when I taught in the classroom, the students were careful to not mess up the pictures. They knew that I would use some of the pages to make games for them to play.
I love when I find some of my favorite workbooks at garage sales and often in the FREE box. People feel because the pages have been done, the books are worthless. Even if I only can use a few of the pictures, I am sure to grab it.
I will also buy books, knowing I am going to put them straight into my cutting box. These, of course, I hope to get for 25 cents.