The first obvious place is the shopping channels... After that, there's the Official Forums, they have a place for you to sell. Just remember that the shopping channels are area specific, if you offer something for sale when you're in Old Athen, you're not going to get any buyers from Borialis answ...

Ive started blitzing at lvl 40 only, but now I cant seem to sell my 2 pairs of Gahalad Beyer pistols...

So my question is, how and where do I sell stuff?

Thanks