In the past few years, we have covered plenty of gear for strongman training. These Rogue Husafell Strongman Bags are also worth a look. They are made from 1000D MIL Spec Cordura with reinforced, double-stitched seams. Sand can be added conveniently using the hook-and-loop funnel filler.
These bags are available in 100lb to 200lb versions. Sets you back as low as $125.