So if you want to get the seventh Technopriests book, the second part of I am Legion, the eighth volume of The Metabarons, or any other book in the Humanoides catalogue that isn't out yet or wasn't translated into English, what are you to do?
Buy the French editions on the Internet and get a sympathetic French-speaker (easliy found on most message boards) to translate them for you.
If You Live in North America
You're in luck, you don't have to fork over wads of cash to have books shipped from France.
You can order them from Quebec!
The two biggest French bookstore chains in the province have websites where you can buy (among other things) bandes dessinées.
They both have English versions of their sites if the French proves too difficult for you.
(I really have no opinion on either store's web presence, as I only buy from their brick & mortar stores.)
If You Live in Europe
(And by 'Europe', I mean the UK. Because if you live on the Continent, chances are you aren't an anglophone, and you can buy this stuff at your local bookstore, in your native language.)
I only know of two, since I don't buy stuff over the Internet. If someone suggests more, I'll add them.
Just from the point of view of browsing (I use them to find out release dates for the French editions of manga), I prefer Fnac because it seems more organised. It allows you to search by series, which is really, really useful.
I don't think their sites have English versions (as they're aimed at unilingual francophones), so it might not hurt to get a little basic French under your belt.