That is a really good question, Helen, and I hope many people reply.
By ebook you mean an electronic text, rather than audio, right? I have not tried this, as I’d rather buy physical books. Nevertheless, it seems to me that you should have no trouble with being allowed to purchase the material, as regular printed texts are freely sold from Russia to people outside the country.
But I can tell you about my experience ordering from Russia. Recently I’ve bought most books from merchants outside of Russia, however, in the past I ordered from www.ozon.ru and some other online bookstores w/in Russia. Ozon is the only one for which I remember the procedure well. Payment was by credit card: after filling out my order I would be switched to another site which handled the monetary transaction. This always went smoothly on the Russian side. The only problem I ever had was, initially, interference from the American credit card company, which was concerned that as I was buying far “out of zone” my credit card might have been stolen.
It is possible that Ozon or other merchants will or have started to use Paypal, which now has a presence in Russia, I have read (via Singapore, I think), should that be of interest to you.
Ozon charges a bit more than most other online stores, but they have a nice site w/ lots of information, their inventory is extensive, their procedures are not difficult to follow, and they pack their merchandise well (nowadays), although the last won’t matter for ebooks, which they do offer.
You can find other online bookstores here: http://www.findbook.ru/ . I ordered from Болеро and Чакона awhile ago, and was quite happy with them.
You might try www.setbook.eu . Until they dropped almost all audiobooks from their inventory, I was very happy with their U.S. counterpart, www.setbook.us , other than that the packing of their parcels was pretty awful. They too offer ebooks, I think.
On a related matter: audiobooks are a problem. Sellers used to ship them from Russia, but now they will not. It seems they are forbidden to do so by law, for some reason. The most economical vendor outside Russia that I know of, which had a large inventory, just a month or two ago stopped offering almost all the audiobooks in its catalog. Do you, or does anyone know of a good source of audiobooks in the West?
I hope this was helpful. Please ask if you have more questions.