I would say ALL people on this forum that sell, ask buyers to pay by either Paypal (most do this), Check (most with stipulations involved) or Money Order with a combination of these. I've never heard of paying by Bitcoin or Ripple....until now.
IMO - If you want forum members to buy your books, I would HIGHLY recommend you accept one of the above forms of payment or a combination of the three.
This is a mostly a "community" of comic collectors and most of us try to look out for one another on here.
Enjoy!