FWIW, eBay on CJ has been about the only decent advertiser for me. And Google AdWords pounds it badly for sheer earnings. ABEBooks did well for a time, but then they started throwing reversals of 70% or more - in other words 70% of sales I generated were refunded to the customers, allegedly. That was about a million miles from acceptable as far as I was concerned, so they were summarily dropped. Almost every other advertiser has made 0% sales for me over the space of a few years.