Welcome aboard, I guess I have been doing the same since forever.
Among other markets I frequently scan GUMTREE:
https://www.gumtree.com.au/
for good value 2nd hand items.
Have also found excellent value on items here at IceInSpace forsale listings.
Also have on occasion found good value on discontinued and obsolete lines on various merchants websites (scratch and dent etc).
It is often a matter of expending time and effort in tracking down big savings and even unobtainable items.