Anna, you folks must have "rock shops" over there where folks sell crystals, meteors, smooth river rocks, and mineral specimens.

When you get a moment, go a visit. Usually these places have a basement full of all types of vibratory and liquid based tumblers going. Ask if you could purchase one "as is" and used.

If you chose Lortone, the best in my opinion, that sucker will churn for decades with minimum maintenance and the replacement of a rubber gasket or two.

Hope this works for you. I love mine.

@Silverleaf: There was discussion in another thread about kiddie tumblers working. I think it was the one I linked to by my name.

@Polyanya: I agree. It is something that would pay for itself over time.

@Freda: That is good to hear. Maybe that will help Silverleaf with her decision.

I'd love a rock tumbler but even the cheap kiddy ones are like £30.

Anyone know if the cheapo ones are worth it? I figure clay's much softer than rocks so it shouldn't take as much effort to sand it.

Desiree McCrorey was the first person I saw suggest tumble-sanding with rocks, and I used her process as the starting point for working out what suited me best. She describes TWO passes of pebble-sorting, with a first pass where she selected the smoothest and roundest pebbles for use in her first tumbling stage which she estimated at 400-500 grit, and then a second pass where she picked the smoothest out of those smooth rocks for a second tumbling stage which she estimated at 700-800 grit.

I just do a single tumble-sanding stage, going straight to the "smoothest of the smooth" (had to pick through a LOT of rocks!). However, I also tumble with MANY more rocks than beads in my vibratory tumbler, and only a little bit of water, so those may be factors in how effective they are. The end result I get is a bit better than 800 grit, anyway, and I'm very pleased with it.

Oh, and Desiree said on her web page that "Unlike sandpaper, river rocks as a tumbling media will last forever." She's been tumble-sanding for years more than I have, so I reckon that sounds promising!
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@Freda: I don't really know. I think the only way the pebbles are going to stop working is if they become smooth. And if that were possible just by tumbling alone without any substrate, then all the pebbles on the beach would be polished. I suppose if it did happen after lots of tumbling, you could just replace the stones.