tedster - 6:48 pm on Apr 19, 2013 (gmt 0)
if you offer a discount for some reason and sites link to you highlighting that, then that is entirely natural
However, in the Overstock.com case, the company actively requested return links from university web pages. I can't say for certain, but that action may have crossed some thin line in Google's view.
I agree that it doesn't sound very egregious, and there was some buzz back then that other link building actions were also part of the total picture.