IMO, the cobra buckles add a lot to the cost of a harness. If you are jumping or roping, they are necessary, but for normal use, the plastic buckles are fine.
My regular work harness has plastic buckles and has years daily use on it.
ETA: the harness in your post is one I use frequently and the build quality is very good for the price.
When a dog saves the life of a man, it becomes clear that partnership knows no bounds.
Fama - T.E.D.D. OEF XI-XII (GSD)
Marshall - T.E.D.D. OEF XII-XIII (Lab)
Lucian - Med Alert (Cane Corso)
Pud - the old man (Pit x Lab)