I have a Thumlers B that I bought used, several years ago for about $60.00. It was the slow version, a rock polisher. I too replaced the axles and have gone through 2 or 3 belts since buying it. A couple of years ago I updated the slow speed motor to the high-speed one. It still cleans and polishes to the same level, it just does it in half the time it used to. Mine gets used with stainless pins too. Any concerns over brass damage are unfounded, 99% of a steel pins surface area is smooth and polished. the remaining 1% are the ends which are sheared rather smoothly. These are the areas that primarily clean the primer pockets, and the inside of the case at the top and bottom.
I also have two old Lyman tumblers, both over 30 years old, and I did wear a hole in the original Turbo 600. I replaced it with a newer design Turbo 1200 bowl and it hasn't had an issue since. My original Turbo 1200 is starting to get a little weak now, I should hunt down a new motor for it since I fix and keep everything else. This one is at least 10 years older than the Turbo 600. In addition, there is a Thumlers vibratory tumbler I bought used a few years ago. It's really energetic, and if I had to buy a new vibratory tumbler tomorrow it would probably be another one just like it.
And finally I have a really elderly Vibratek, and a noisy bastahd it is, too. It's the large Vibratek, I was looking for a small one but couldn't resist the price. It came with the Thumlers vibratory, free. I bought it to try using a flat type vibratory tumbler for powder coating bullets. The Vibratek uses plastic bowl, and this one came with a lot of properly sized ice cream tubs. Maybe I'll get around to trying this yet. No guarantees...