Obtaining links from the same sites/pages that link to your competitors is a fundamental
SEO tactic that should always be followed. I wouldn't be too concerned with 'related' links.
Many feel that *all* links are valuable. I agree.
Keep in mind that finding your competitor's backlinks is so basic (and popular) that Google has changed the response to their link command. There was a day when all (or most) links where displayed. Now, my guess is that only about 10% are displayed. And, those that are, tend to be mostly the junk links (forums, blog comments, etc).