While you can occasionally find deals, the GoPro has a minimum advertised price. You will not find a price lower than retail advertised by any dealer -- if they do and GoPro finds out about it they will no longer allow that dealer to sell their product. This doesn't mean that resellers won't offer a better price, in fact I have been buyi g from several Moto shops here in the PacNW, and when I decided I wanted one, I asked them all for a deal. All but a couple offered me between a 15% and 20% discount just for asking "What is the best price you can give me?"
Occasionally, an online reseller will offer a general discount coupon (ie: 15% off of your order) and you can use that to get a discount.
To answer your original question, I am not aware of any current coupons that are out here, but I would go to your favorite moto shop (or other adventure sports store) and ask for a discount. The worst thing that they can say is no.