Cool, take a look if you care at a revision of a design I found online
I found the info here
http://hybrid2.honda-perf.org/contrib/cameramount/buildit.htmlbut modified it and made it better here.
http://thor.prohosting.com/~nfredly/Cam/camhowto.htmlabout $7 at home depot, and about $25 more at a good camera shop
for a mount.
To help stabalize the seat/camera I use a small cargo strap probably like $4 at a walmart or something.. I had one so no cost.