Hrm. The best place I can think of would be "Classifieds" (it would have been better with its previous name, "Deals") but we don't currently have a sub forum dedicated to something like that. We've made a few attempts at something like this in the past, namely the "Best Deals" stickies you will find in that section; it never really took off. If there is sufficient interest in something like this, I'm sure we could set up a thread or two for the sharing of unwanted vendor coupons.