I think that most of classifieds allow this, and you can promote other Affiliate programs, not just Amazon, so this can be solved.
or even better: CPA networks
i see the problem in this case is the same as always: a lot of people who read the thread want to replicate exactly what OP does using the exact same site and the exact same network for monetizing
however OP even mentioned that he doesn't use CL for this, but other classified sites
idk why everybody's talking about CL
classified sites =/= only CL
OP's method works, the other method what the other guy posted above also works, you just need to replace a few or even just one piece of the puzzle
Amazon doesn't like this? fine, let's find a network which does, you can't find any affiliate network for this? no worries, there are countless CPA networks (but you need to make sure that they allow classifieds promotion, i prefer being straight w/ the AMs, so i just tell them what they need to know about the traffic source, if they allow it, it's fine, if not, i just switch between networks)
you can't post on CL? no problem, there are other classified sites out there, sure thing that CL is the biggest, but why not post on a bunch of smaller ones instead to get similar results?!