Many years ago I tried making and using a short wave crystal set. It is on my website. As you can see, it does not cost much to have fun. I had aims of making a crystal set that covered VLF to VHF. Then my stroke scuppered plans!
Short wave radio is changing and there are far fewer English language broadcasters. I was pleasantly surprised by what I could hear back then. It is not just broadcast stations you can hear.
See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing .