Are there any affordable treatments that could cure bone cancer stage four?

Maybe/hard to say.: Most of these are resistant to chemotherapy, so often surgery is done, with good results. Both of these are expensive, but chemotherapy may be more so, and many cycles may be needed. So you may be getting a less expensive treatment. Ewing's sarcoma can be cured with high dose therapy and bone marrow transplant, it really depends on what your cancer is and what works, and what your plan covers.