The cleaner is called "LA's Totally Awesome," and is available at Dollar Tree and other larger dollar stores at VERY low cost. Basically submerge your models in a plastic container of some sort for 6-12 hours. For some of them, paint started to flake off in big chunks after less than an hour. Once they've been soaking for a few hours, take a soft-bristled toothbrush and gently brush the paint off the model. In most cases, it'll come right off, but if it doesn't, just let it soak for longer.
The best part (in my opinion) is that it seems to work on all kinds of paint. The GW brand, Testor's oil-based paints, enamel and acrylic. The oil-based paints take longer to come off, but it DOES come off. It does NOT dissolve/melt/deform plastic models, though I haven't tried resin models yet.
The only downside is that it will also dissolve some superglue. However you can use that to your advantage, if you are trying to salvage components or re-do a botched glue-job without breaking a delicate piece.
