I found some really cheap printer paper that is thin at a dollar store. Just check it out to make sure. But also I found out from a real paper piecer( I am new to it) to use regular school three ring binder paper. There are two sizes, get the larger one that is the same size as printer paper. It works great. Good luck. I love paper piecing, just am a beginner and so I don't do complicated patterns yet.
Rita