It really depends on your budget for the most part, I'd also take in to consideration your long term business goals and the industry you compete in.
Whether you go in-house or hire an external party you will get what you pay for, like anything in life. The advantage of in-house is they are in your office and their job security will eventually come down to their performance.
On the other hand an agency will be cost effective and have more than one SEO specialist at their disposal with the bigger benefit being that at least on of their SEO guys will have been in the industry for somewhere around a decade.
If you want to discuss it in more detail I'd be happy to advise you on the best path to take as it's hard for me to make a case for either without a better understanding of your business and business goals.
I'd honestly be looking at better ways to invest my time, however, to answer the question I'd think some do-follow social bookmarking to each of those articles would work. Although I can think of better ways to spend money...
@Markbrook, the disavow tool is to exclude inbound links, you simply upload a file with a list of all the urls pointing to your site you wish to have ignored. It's been introduced as a result of the of the Penguin algorithm. Shame it's taken them 6 months to roll it out, poor effort on their behalf in my opinion!
The easiest way is pay someone with a proven track record, they know what they're doing and have the resources for link building.
Otherwise you need to be prepared to learn, and invest the time, to work on the site, build (or purchase links) along with keeping up to date with changes Google make.
Working on the site isn't so bad, once it's done you only need to change it up if something major changes with Google's algos. The link building however is the harder part, it's either very time consuming or it's time consuming and expensive to find good links or link builders.
It's a big ask for someone to sit here and give you the A to Z on how to get your site to page one. Put it this way, to answer that question is about a 20 to 30 page book, I know because I've written one lol.