Using ReStockit as an example they have commissions varying by item from 3% to 10%. In the CJ interface they have the rates listed and a link to the products for that commission rate. Fine if you are doing PPC you can shop the higher yielding products.

I like to use their feed and the problem is that in the feed you can't see what the commission is for a given product. In this case the AM was responsive on the phone and is seeing what can be done.

CableOrganizer is another one I would like to promote with their feed. They have 3 levels from 2.5% to 11% and in their terms it says:
(Please note The CableOrganizer datafeed is setup with product categories denoting item based commissions. 687 lower margin, seldom purchased items are displayed at a 2% commission. Another 13,124 lower margin, seldom purchased items are displayed at a 5% commission.)
It's not in the feed that I can tell, and Durk Price is checking into it.

Some item based set ups are easy like when they have sale items one commission and every thing else another. There seem to be more and more of these complicated commission structures these days.