you can make your own if you want

http://www.alternativephotography.co..._dryplate.html

it isn't too hard, and a lot of fun

you can find recipes for emulsions here on apug
http://www.apug.org/forums/forum205/
or at the light farm http://www.thelightfarm.com/
or you can buy bottled stuff from liquid light, or the formulary
there is someone in costa rica also making emulsion for sale as well ...
http://www.costaricacoffeeart.com/al..._or_plates.php

have fun!

john