looks like they may have it here. i just googled 'walking foot for brother VX-809'. there were lots of results, so you may find it elsewhere. but it is specifically listed as a machine that this particular walking foot fits.
http://www.sew4less.com/product/2034...ing_Foot_10449
the price seems much better at the following site. also, if you scroll down to the bottom of this page, you'll see a handy little drawing that shows the difference in the feet and how they attach.
http://cgi.ebay.com/Walking-Presser-...QQcmdZViewItem