As I write this there are 3,653 hits when I search Ebay for "Japanese sword".  I would guess that something like 50 of them, if even that, are the real thing; the rest are modern fantasy pieces, modern reproductions, and out and out fakes.  To make matters even worse for the beginning collector, there are fraudulent listings: stolen descriptions and pictures, hijacked Ebay identities, and more.  Given the high value of real Japanese swords, buying them sight unseen based on a couple paragraphs and a few pictures from someone you don't know is not for the faint of heart.
    Ebay will allow only 10 pictures in a guide so I've used my ebay 'ME' page to present a side by side comparison, complete with lots of pictures, of real and fake Japanese swords.  I also discuss sword scams on ebay, sword care, polishing, and a few other items you might find useful.  If you'd like to see it you can get there by clicking on this link or by searching for seller greyguy0 (that's the # zero, not a capital o) and clicking on the ME button there. Once there, please come back to this page and rate my guide.
    Hope you find this helpful; thanks for looking.  Take care,  Grey  (greyguy0)