Unless you KNOW with certainty that you are a 'macro shooter', and you wish to use an extension tube only for occasionally closer focus than MFD, you might be well served with very inexpensive extension tubes.
I have been involved in photography for over 40 years, have equipment in four different format sizes, and (when only film was available) I had abandoned 135 format shooting for professional purposes, as I felt it gave me inadequate performance. That gives you an idea of my level of expectations regarding IQ. I have expensive extension tubes for my medium format film camera -- ONE tube cost more than an entire Kenko set of tubes for Canon (simply because no inexpensive third party tubes were offered on the market), and I used one of the tube lengths simply for more tightly framed headshots. I am NOT a routine macro shooter, it has little inherent interest for me when shooting recreationally.
I still have high standards about IQ, and I never ventured into digital SLR until I felt it could rival (as a minimum requirement) what could be achieved with film. Nevertheless I 'cheaped out' ($50) when buying a tube set for my Canon digital kit...tube set made with composite material including composite lens mount (not metal) but with electrical contacts. I can stack all three tubes and the body can still communicate with the lens. I can focus closer when I want to frame tighter. I still don't routinely take macro shots.