White spirit is cheap and can be reused, and works very well in terms of cleaning, though you might not want it splashing everywhere.
The Barberi stuff is quite effective and safe. £5.20 for 250ml from InMotionProducts.
However, I've gone off the idea of using cleaning devices or immersion as I fear it flushes as much grit into the chain as it gets out. I just let the chains be now, except for wiping crud off the outside with a rag soaked with white spirit, then lubing.