Google trusts .edu sites. This is not a rumour, but a fact. Schools and universities and other entities that focus on education usually own such sites.
An inbound link from an .edu site bears higher authority than ordinary links, simply because Google considers .edu sites relevant and important for the users. Because they are so valuable, .edu links are difficult to get. Besides, .edu sites do not focus on profit, so there are low chances for you to be able to buy one.
Some people try to get the valuable .edu link juice by spamming .edu blogs or .edu forums, but this technique, although somehow effective, is very dangerous: Google might penalize your site if you have too many .edu links with the same anchor text, pointing to the same page, etc.
So how do you get these precious links after all? This is a problem. As any other valuable SEO resource on the Web the .edu link was abused too. Most of the .edu sites do provide for quality inbound links. However some are exploited by text link brokers and other profit centered individuals.
You don’t want to buy a link on an .edu site because buying links is seen as a black hat technique by Google (I am not referring to the type of text links that appear as sponsored links or sponsored ads).
You could post a job advertisement in an .edu job board like this one, but don’t do it unless you really have a job opening.
Join an .edu forum related to your niche and start posting quality entries (answers and advice) to affirm yourself as an authority in your field. Some forums do allow links in your profile and they are not marked rel=”nofollow”. That’s it. Good luck.