I just finished editing a video of how to use a Pi as a DMX bridge. Quite useful. I will probably be using a couple of these next year. http://alpharoadchristmas.thruhere.net:8089/how-the-display-works/22-how-it-works/other/50-raspberry-pi-dmx-bridge The dongle I used is linked there, but it is available on Ebay and Amazon. This software works on the Pi Zero, which costs just $5. You will need a small adapter for the Zero, as well as a way to connect it to your network.