Just a heads up the OfficeMax $10 for $20 Voucher from Living Social can be
stacked by buying gift cards. Maybe the vouchers can be stacked anyways?
Im not sure I just know the voucher works on gift cards which is rare. Of
course only one voucher per account
Link: https://www.livingsocial.com/cities/66/black-friday
Also by buying a gift card you extend the life of the promotion
PS: Lowest gift card value is $25