You can pick up one of these cement mixers at Harborfreight for $150 bucks. Take out the mixing baffles and spray inside the drum with truck bed liner. Add your media of choice and flip the switch. During a factory tour of Sierra Bullet and sister company Starline brass, both were using very similar setups (larger scale) for finish polishing their products. IIRC they were using some sort of metallic media, that appeared to be tiny SS beads.
All that being said I have seen first hand what the wet SS needle media can do. Another member here (Blademaker) has a nice setup that uses that SS media, his only complaint was the cost of the media. However the results obtained with the SS media is outstanding.