I've checked the marketplace on DP and I've noticed that links in posts/articles tend to cost more than those on the blogroll(sitewide).

I feel this should not be the case considering that PR for homepages rank better than pages. Aside from this fact, blogroll links ARE sitewide. The small investment for the blogroll is thus maximized as opposed to links in articles which even has the chance to be

1. not indexed,
2. not get PR

On the other hand, the only pro reason I can currently think for links on posts is that those tend to be permanent.

Would appreciate your thoughts.