Well, a long, long time ago, when Jesus and I were standing on the trap line wearing sandals, I used to do a lot of shotgun reloading.
I was shooting, on an average, 500 rounds a week. That was when shotgun shells came in boxes of 25, and 20 boxes to a case. the cost for Winchester AA shells was around $50 per case ($2.50 per box).
My reloading costs for 1-1/8th ounce of 7-1/2 shot, 3 dram loads of Red Dot, using WW primers and wads was 85 cents a box. I probably could have saved a few cents a box by using different primers and wads, and saved even more if I used reclaimed shot ... but that wasn't for me!
Was reloading shotgun shells worth it? You bet it was!
I have no idea what it costs to reload shotgun today, what with the rediculous shipping and hazmat fees (I used to buy shot a ton at a time, primers and wads 10,000 at a time, and powder 24 pounds at a time.)