Give this article a read (click here). In the article, vendors are clearly taking advantage of their clients to pad their own profit and loss statements.
I've been there. One of the co-ops that catalogers trust offered to give me a percentage of your money if I funneled business to them.
This means that the co-op is over-charging you, right? If the co-op can afford to take a half-penny of the +/- six cents per name they charge you and deliver it to my bank account, then the co-op can afford to charge you less. It means that you are paying a premium to the co-ops so that the co-ops can fund the vendors they have cozy relationships with.
Why should you have to fund cozy vendor relationships?
Buy the booklet (click here) and set up your own Vendor Accountability Summit. During the Summit, ask each vendor to publicly announce their financial relationships with other vendors. Watch for changes in body language, red faces, heads hung low, feet tapping, hand wringing, eye glances at each other, that kind of thing.