Decent size chain is ridiculously expensive. Try to get some second hand chain that is being thrown out. You can try shipyards, boat clubs, drillers, crane operators or any other business that uses big chain and turns it over. It will be rusty, but much cheaper.
I scammed 70kg+ that work was chucking out and cut it into 5kg lengths (~1.5m) and bought a bunch of 30c aluminum carabiners so I can make loops (I can sling over my shoulders) or join lengths together with.
I de-rusted my chain with rust convertor (phosphoric acid). It's now grey and dusty but not rusty and staining everything. I might try some in HCl and see how it goes or cover it in paint/protector if required.
I don't use it much, but it was cheap steel and I do find uses for it. Mostly just as additional weight.
The missus would love some bands to learn to chin with etc, but I just help her instead. I don't have much interest in trying bands for squatting or anything.