I wouldn't worry too much about PR as it plays a less significant role than it used to. Concentrate on building a lot of good, unique content. As far as links go, I think content will overweigh the PR leakage you're worried about.
Keep in mind though that search engines can tell the difference between regular links and affiliate links. Affiliate links can greatly hurt your search results placement, and also lengthen the time it takes for your website to get indexed.
For example, I have two websites which I launched at about the same time. This was about 6 months ago. The first website was built using a ton of affiliate links, and to this day has not been indexed by Google. The second website had no affiliate links whatsoever, and this site was indexed almost immediately. I am not saying this is always the case, but more often than not.