Hi Adam,
Why don't you just use HTAccess. Then you can mask all your links even if you post them in your forum sig on on your social network profile and even in an article you submitted to 5 article directories, which you can now not go back and edit.
Lets say you have a link in all 8 places for a product - your blog, forum sig, social network and 5 articles. That merchant goes under or the product is obsolete and there is a better one. How long would it take you to find and change all the links if you even remembered and if you could still edit them?
With HTAccess you go to one place, exchange the new link and ALL YOUR LINKS, even ones you fogot you had out there, even the articles that can no longer be edited - they all re-direct to your new merchant now.
With HTAccess I would give the link a generic, but KW rich name instead of product specific, in case I ever did need to swap it out. So instead of .com/ABCluggage I would say .com/bestluggage or something.
Above I'm just telling you the advantage of cloaking with HTAccess, not how to do it, because maybe you already know how. There are also other general ways to cloak. If you want more info just ask and we'll give you some more resources. But won't unless you do cuz possible I just wasted my carpal and you have a specific reason for wanting a WP plug-in and didn't need all this info.
Link Masking Plugin for Wordpress, looking for one
Linear Mode
