In the states, it usually translates to something like a pint of Bud Light Lime at BW3s. Or in my case, three 24oz cans of Busch at the local bodega.
In the states if I bring out 10 books and sell them each for 10 dollars and don't lose, misplace, or give away any of them, i might pocket about 20 bucks. The key here is that i've almost never been to a tournament where I've sold 10 books or more.
When I flew to USA College Championships, i brought 8 books to sell. Then I left them in the plane. Haven't been recovered yet. So that's a loss.
In any case I am pretty sure the publisher is doing ok. I'm selling the books, he sits in a canoe somewhere, automatically has the warehouse send them out to Amazon, B&N or wherever and they send him checks. Actually, I order books with my half-off-cover-price and pay for them on my AMEX. Since the publisher put the price at $14, i get the books for $7 (recently re-negotiated to $6). Then add shipping them to me. Then realize that no one in their right mind would buy this book for $14. It's not even in color!
So I sell them for $10. But for Worlds, I'm going for the gusto: 12 euro. Comes with a free can of Busch. in Prague, that has to be special, right?
Don't worry by Friday night all the books will be discounted to 'cost + Staropramen pint.' And I hear the beer is cheap over there.