You can purchase carbon fiber tubing just about anywhere. Just search for "16mm carbon tube" (or whichever diameter is appropriate). E.g.,
Etc. Sorry those links are clickable; as a new user I'm limited to only 2 links per post.
I'm less certain about the motor mounts. Tarot makes similar but not identical mounts that are widely available; maybe if you can't find matching replacements for your U580 you could just buy a set of 4 tarot motor mounts (e.g., these, which designed for 16mm carbon tubes).