I don't get it, when you get your aff code, the code will redirect you to the sales page once you've enter?
If you're talking about direct linking in PPC, I would advise against it. The QS will be dead low and you could get suspended. If you're talking about direct linking to the order form page, I think only a few vendors do that. I'm not sure, but I'd advise against that too, since many top vendors put a huge amoutn of money and testing towards long, effective copy.