Have you tried looking on Shoptemp.net or the R4i Gold Plus manufacturer's website for a list of retailers?
Shoptemp lists a number of retailers from all over the world and also allows customers to leave feedback, so you can hopefully find a shop that WILL accept payments.
Even so we don't recommend the R4i Gold Plus, it is not a good flashcart. You more than likely want the correct R4i Gold model which supports Wood R4 firmware.
Or if it's the enhanced features like real-time saves you were interested in, then it's the Supercard DSTwo that you actually want.