You currently have a trilogy, so I would suggest a basic wgp vert feed as a good, "real" autococker to learn on. The cost of entry will be relatively cheap compared to a new or used ccm, and there's a plethora of used parts for very good prices. Ans and wgp parts are excellent bang for the buck products. I've had excellent ans and wgp autocockers that were solid performers(weekend day/night scenario events without any issues.)
It would be best if you could pick up a complete, leak free, and well timed/tuned autococker from a reputable member, that way you will have a frame of reference for how it should feel/shoot.