Elric,
ebay in the U.S. used to be a great source for inexpensive, used Russian books, but now it’s not so great, although there are still some good buys there, I’m sure. As w/ the other U.S. merchants I’ll mention, shipping to Brazil must be considered, as you say, but I do not know the rates. From Russia the tariff depends on weight; I would guess you’ll have to spend at least $15 U.S. (but that’s just a guess).
A convenient page to find links to Russian online bookstores is this: http://www.findbook.ru/ . Some of these are used-book sites–for instance Alib.ru and Buklit.ru. The only ones listed on this page that I’ve dealt w/ are ozon.ru, Чакона, Болеро, and setbook.us (not the .ru listed on the page, but a sister site), and all of those for new books, not used. All were quite satisfactory, and I would re-order from any of them.
I don’t see used books in there [on ozon.ru]
go to книги (on the left of the main page) then to букинистика (part way down the page). Or search for an author or title and look for the description “Букинистическое издание” under the titles found. I have never ordered used books from this site (or from any Russian site, as I said) and do not know how the transactions would be handled–whether ozon ships the merchandise or the actual vendor does, etc. If you ever try ordering used books from ozon.ru, please let me know how things go. ozon.ru is dependable, and has a great selection and website (which used to be even better, IMHO). They also pack their merchandise very well, which cannot be said of some Russian merchants. Their prices are a little higher than most online outlets.
Audiobooks, if you’re interested in them, are no longer shipped from Russia to destinations in the Western Hemisphere, as far as I know, although they used to be. I do not know what the reason for this is, but my guess is that as they are on CD they are classed w/ computer programs and thus not to be exported. Whether you can successfully download audiobooks from Russian commercial sites such as ozon.ru I do not know.
New Russian book prices are still significantly cheaper than those of new U.S. publications, generally. You might look around at some of the Russian bookstores online to comparison shop, if you have not already, and find prices w/in the range you’re interested in. Or try these sites in the U.S., which I have ordered from in the past:
http://www.setbook.us (where I usually shop, although they too have stopped offering most audiobooks)
http://www.ruskniga.com/ (quite dependable)
http://www.kniga.com/ (okay)
Also, here are addresses of merchants that I have found but not ordered from yet:
http://www.bukinist.com/
http://www.russkieknigi.com/ (judging from their prices, some of these books may be used)
http://www.priviet.com/ (audiobooks)
http://www.kniga.ru/
Surely there are lots more good booksellers out there; if you find anything worthwhile, please let me know, especially if it offers audiobooks.
I still don’t have confidence enough on my language skills to deal with an online business 100% in Russian.
The first time or two is rather unsettling, but I bet you’ll have no trouble. Browse around those sites. You’ll probably find they are great aids to building your knowledge of Russian, as they’re so interesting to a book lover, and maybe especially to a science fiction fan.
(Brief, as always :))