I started loading 12 gauge shells in 1971 with a Lee Loader. Shot was about $6/25# bag and powder was $8/pound. I could load a box of shells for about half the going price of factory loads.
The costs of components changed over the years and for a long time, it was just as cheap (cheaper if you count your time) to use budget priced "value packs" from WalMart for informal clay bird shooting, doves and quail. Hunting ammo, especially magnum loads and steel, could still be loaded for less cost than buying.
I still have two MEC 600s (12 ga 2-3/4" and 12 ga 3") and a MEC 650 (set up for 12 ga 2-3/4" target loads).
I used to binge load shotgun shells, a thousand of any given type at a time, and I am still shooting hunting ammo I loaded in the late 1980s. I've shot up most of my trap/skeet ammo stash.
I really don't think one can save much money any more, probably enough to use equipment you have, but not enough to offset buying new gear
My shotgun shooting volume dropped off and I seldom load shotshells any more. I hunt waterfowl a couple times a year and a box of shells will last me all season, sometimes two seasons. I shoot sporting clays for fun and burn about 100 shells a session and couple times a month and typically use cheap factory ammo.