I use a small 2500 series Jobo tank and a 2509N reel, not on a roller base but with inversion agitation. Used this way the tank uses about 1400 ml. Compared to a Combiplan, the 2509N reel is much easier to load, the Jobo tank doesn't leak and it's much faster to fill and empty.

Just a tank and a reel doesn't cost that much, and you don't need a processor.