I got one off Ebay last week for 30$, the usually go on ebay for like 60$. I'd say go to a junk yard but you will never find a s13 with a sunroof shade (although I got mine from a Junk Yard that sold it on ebay). So try your luck at the junk yardand keep your eyes open on ebay.
Its summer BTW, quit thinking about the cold ass winters <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> hehe