Can anyone elaborate on the ARe by 10 get 1 free deal? If I buy 10 - $0.99 books can I select any eligible book for free or is there a price limit based on how much the books I bought cost? Since I'm going to buy 4 of the JALs and BoB and it's discounts are gone

, I think it might be worth it to give this ARe deal a try.
Is there anywhere you can view how many books you may have already towards this credit?