I understand the back & forth until an agreed upon price. But what's the unspoken rule of thumb for exchange of credits? 

Thanks! 

Kate

You don't exchange credits with Box of Books.  The whole point is to exchange book for book with no credits.  How it evens out is up to the boxers in each trade. Usually it's 1 for 1. But sometimes people will do uneven trades: if for example 1 person has nothing but little seires romances and the other has all full length books-the 1st person might agree to give extra books to the 2nd person.  When I was a boxer, a couple of times I didn't  find an equal number of books I wanted on the other person's shelf-but I let them have an extra book or two just to move them out of my house.  (and if they did have something I really wanted-I never did trades for books I didn't want). 

I wouldn't suggest doing BOB if your bookshelf is loaded with books you would never read yourself.  Because that's what'll be on most of hte shelves of people who make you offers.  Although a lot of boxers do have large varied shelves. 

And it's ok to say no.  You don't have to accept every offer made to you. 

Also it's not for WL books.  Only for books available in the system already.

While I agree that the point of BOB is to exchange without credit, I've been involved in several trades where a credit was thrown in to even out a fairly big discrepancy in the number of books wanted from each side.  For example, if I wanted six books from one series, and the other boxer only found two books she wanted from my shelf, I might throw in a credit or two to help even things.  Certainly, I could have removed books to make it even enough to be acceptable, but if I want all the books, adding a credit or two into the mix is preferable.  Or a BOB offer might turn into a "deal" instead, if one side found nothing they want from the other's shelf.  I've done that, too.  Someone wanted three of my books, but I wanted none of theirs, so I offered to do it for one credit.  We cancelled  the box, she requested one of my books on a regular order, and I tossed in the other two as freebies.