If you are handy with photo editing software, you can do them fairly easily yourself. I like Microsoft picture it, but that's mainly because its all I have so I know it well. I just take a picture I like, cut out the calf or whatever, then fill the new cut out calf with a solid color. you can also create an outline on the cut out animal then change the fill to white or transparent for only the outline. I am going to work on some and get them up here when I have some free time.
I would do some Google image searches for now though