Yahoo! Answers is bound to get harder and harder over time, more and more people are trying to market Yahoo! Answers, so more people are flagging questions/replies and making it harder for everyone else to make some money with Yahoo! Answers. My advice is to create a genuine post, wait a few days, then reply, then wait a few more days, then select your answer as the best.
The landing page of your traffic is vitial to keeping your answer to stick, if you simply directly link to the page, it'll be removed, if you use something like tinyurl, it'll still be removed, simply create a blogspot / wordpress blog, post around 10 posts on the niche, then post 1 post on the product your trying to promote, with a review and what not, then push to that page (On your blog), which links to the landing page.
Seems like a lot of work, but if you have 1 blog, you can easily push 100 products on that one blog, so it really isn't a problem, plus your gaining back links to your blog, do a bit of SEO on the blog and you might even be able to get some genectic traffic to your blog and make even more
