I bought my first one on ebay. They are called "public jigs", "duck call insert jigs", and a few other names. they are called public since that is the common jig used by most to get started. They usually run around $75. If you have a friend with one that can get you one made by a machinist they still usually run between $50 and $75. You can also make your own from wood. Just a few dimensions: 2" block of hard wood, 5/8" hole drilled through the center, cut the block so that half of the hole is showing (look at your photo). Not hard to make just be sure when you use it you don't cut it up too.
