on our campus every one has this in their colors and some members receive them in "family" colors as well. they are widely available, come in a variety of colors, and are easy to order in bulk or alone. i recommend them from this company in particular as they provide a slender sleeve (which as girls we preferred) where as some companies (including our local greek store) provide a version with a baggy "chicken wing" sleeve and a white, stitched tag on the front w/ info (ick!)
http://somethinggreek.com/shop/shope...y+Jersey&id=99