This was just posted on COTD facebook page as an exclusive, original price is $29.95 + delivery but with the code is $19.95 free p/h. To apply code:
eCoupon offer valid from today, I tested the Thinkcentre one & it worked on a higher priced system, but not on one that I custom made that was just over $599, see how you go. ThinkPad Laptops