That's a good point. Cheap shafts you should probably consider throwaway if you don't have a cue repair person near you.The cheaper carbons play ok, but the quality is pretty horrible in general. Also the hit and feel seem to be lacking on the ones I have tried. I suppose because you are paying for time and not materials to build these shafts. Very little quality control. Buy a Rhino if you don't shoot much. It will play fine. Kind of like buying that cheap tool because you wont use it very often. Check warranty info. Ask a cue maker what shafts have been coming in the most to get repaired because of failure.
That also brings up a consideration. I don't know if it is still a problem, but the ferrule material in the Cynergy shafts is/was pretty soft. Not a big deal, but if you hit hard, you may experience issues with it. I have had to have a ferrule replaced on one but it was used and may have had an issue when I got it, so YMMV.