Where to find cheap fabric

Does anyone know where I can find cheap silk dupioni fabric? I want to make these invitations but don't want to spend a ton on the fabric!

Invitation:



This is the fabric I want:



Do you think they would have cheap fabric in Chinatown?!

Apparently the pictures don't work so here are the links:

invitation:
http://laineandpete.com/?attachment_id=388

fabric: http://cgi.ebay.com/100-dupioni-SILK-FABRIC-glorious-TEAL-mix-o-green-blue_W0QQitemZ200362321856QQcmdZViewItemQQptZUS_Fabric?hash=item2ea68667c0&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1240%7C293%3A1%7C294%3A50