ColourOfSpring - 7:13 pm on Apr 19, 2013 (gmt 0)
i disagree, if you offer a discount for some reason and sites link to you highlighting that, then that is entirely natural.
I agree with you if they link purely out of their own volition stating something like "hey, great deal over at widget.com, check it out". However, the OP (flanok) did say:-
Is offering a discount on products and services in return for a link the same as buying one and therefore is against Google's terms and conditions?
(my emphasis). It sounds like a conditional or strongly suggested thing. This is unnatural - the discount is purely there to get a link in return.