i don't know where to find images already cut out. but there are a lot easier ways of cutting players out then with the lasso tool.
magnetic lasso (right click the lasso to find this option)
polygonal lasso (right click the lasso to find this option)
after cutting it out, i like to feather it 1/2 a pixel.
hopefully this helps, and btw, i get my images from google, gettyimages (vertical images so watermark doesn't get in the way), and this site posted by one of our members [link