You can buy tippet rings about anywhere. They are very handy for tying droppers or for attaching your tippet to the end of your line. I use them for constructing my two or three part keiryu lines.
These come on a very handy split ring so you can easily tie your line or tippet to the tippet ring before removing the tippet ring from the split ring. That may not seem like a big deal but it makes it much, much easier to tie one onto your line or tippet. Try it once and you will become a believer.Tippet Rings (package of 10) - $8.50