Type "rivco coupon code" into a Google search bar. There are a bunch of results that come up, some offering significant discounts. However, I'll leave it up to you to do the research on how valid they are.
They only do a few a year and usually only to people on their email list. If you’re buying something online you may want to actually call for stock. When I attempted to order a trailer hitch and ball last year their website said it was in stock but they actually didn’t have any.