Most oboe reed making supplies can be purchased online, and in the past my teacher Karen has suggested several sites that she recommends and purchases from herself. If you are just beginning to make reeds and don't have any reed supplies at all, many sites sell reed making kits that come with all the supplies needed (knife, plaque, spool, etc). The following are some sites that I have purchased from in the past:
This is where I have purchased the majority of my supplies - plaques, mandrel, cutting block, cane and beeswax
As Julia mentioned before, MCW has many supplies and is where I purchased my knife as well. The knife works very well and I would highly recommend it to anyone.
Julia mentioned this site earlier, and Forrests is a good resource for a variety of supplies. While browsing the site, I just discovered they also sell this oboe reed making cartoon, illustrated by Bill Bennett....
-Olivia