1. Any local (sand)blasting supply will sell you 5lb of stainless shot 0.025" in dia for about $30. Better than pins IMO, rarely get stuck in primer hole, and are removed when brass is shaken. I only reload pistol brass (for now), and I no longer bother with de-capping first, primers go in just fine.
2. For container, try a round cooler from CTire or Walmart. I paid $15 for the 2gal container I use. I tumble small batches of about 200-250 9mm cases. Not an industrial size operation by any stretch, but I get about 1,000 cases cleaned each week, and it only takes 2min to set up when I come from work, and another 5min 3-4Hrs later. That's where ultrasonics suck IMO, too much babysitting.
I wrapped the cooler with a sheet of galvanized flashing, to prevent the container's core and outer cover from cracking. Ductape holds it nicely together. A also JBWelded a couple of aluminum profile ribs along the container's length on the inside, to help with the stirring action. I would be careful with square containers: unless the motor has the power to take constant changes in torque, it will burn out.
3. There is no dust when whet-tumbling, so a big plus IMHO. Still, I only bring brass that's been cleaned inside the house.
4. Last one: don't use dishwasher soap/agent, they will discolor your brass. Just a 9mm casefull of LemiShine, and a 38Spl case of laundry detergent is all it takes. When done, turn tumbler off and wait 15min for the suds to disappear, then rinsing becomes real easy.