With the cost of a top MBA hovering around $160,000 and Facebook COO Sheryl Sandberg announcing that she "doesn't believe [MBAs] are important for working in the tech industry," it's understandable that most business schools would be looking to add value and reduce cost anywhere they can. At many premier schools, that means replacing physical books with lower-cost e-books.

Montreal's McGill University has now instituted a policy of replacing paper textbooks "wherever possible" to save students thousands of dollars in rising book costs.

But if you're trying to get better at internet marketing, why not just skip the middleman--and massive tuition bill--and dive into some of the amazing e-books available for you to read right now, on the internet, for free?

Here's what should be in your digital bookshelf if you want to be a killer marketer without paying a killing.

1. Qualaroo: The Beginner's Guide to Conversion Rate Optimization

"If your ideas are any good, you'll have to ram them down people's throats," Howard Aiken once said. The truth of that statement is one of the first things you learn in internet marketing. Getting people to do something like click on your download link or check out with their cart or give up their email address is really, really hard. It's easy to just toss your hands up in frustration because you're not where you want to be.

That's why smart marketers like the ones at Qualaroo approach conversion rate optimization like a science and work to make step-by-step improvements. Instead of thinking about how to get your .05 percent conversion rate to 10 percent, focus on the immediate steps that you can take to get it up to even .06 percent. And then .07 percent. And then 0.8 percent. And so on.

Sounds simple, but there are a lot of techniques that go way beyond the obvious ones such as changing the color of your shopping cart.

The Beginner's Guide to Conversion Rate Optimization is a deep and illustrated guide into all things CRO (conversion rate optimization), with techniques and frameworks to help you improve your bounce rate, your landing page performance, your exit rate, and other crucial determinants of how well you're winning customers over.

2. Hiten Shah: The Content Marketing Playbook

After 83 million-plus website visits and 12 years studying content on the web, Hiten Shah has finally put out a playbook for how companies can do content marketing successfully. There's probably no one more qualified to make the case that content marketing is an incredible tool for driving customer interest. Two of Hiten's startups (he's run seven companies over the past 12 years) make millions of dollars a year, primarily because they killed it with content.

For Hiten, it all started with a simple formula:

It takes a lot of work to do effective content marketing: You have to go where your customers go, sit with them, and understand them on a deep level before you can really make a name for yourself in content. Just imagine, though, what your top-of-funnel acquisition numbers would look like if you were No. 1 on Google for a crucial keyword.

Hiten's gotten his companies to that milestone and he has the results to prove it, which is why his Content Marketing Playbook is an essential read.

3. AdEspresso and HubSpot: The Science of Successful Facebook Ads

Facebook ads are one of the most powerful tools at your disposal for customer acquisition. The problem is that getting started can be intimidating. The complex setup menus, the Power Editor, the various types of bid you can choose, different objectives: There's a lot to keep in mind.

When you get good at Facebook ads, though, they can become an unparalleled boost to your fresh traffic. Through ad retargeting and custom audiences, you can tailor the demographics you want to receive your ad down to the most specific of categories, driving only the people you want to your page.

Sounds simple, but a lot of thought and work go into running a successful Facebook campaign, not to mention running several. To get the best results, you need to have a working knowledge of advertising, psychology, design, conversion rate optimization, and lead generation.

That breadth of knowledge required is why HubSpot and AdEspresso's collaborative e-book on the science of successful Facebook ads should be on your reading list no matter what kind of paid promotion you're thinking of running on Facebook.

Read, Learn, Apply, Win

If you skim through these e-books, you'll learn something valuable about marketing on the internet and you'll probably be better positioned to succeed at it than most of your peers.

If you take these e-books, sit down, and study them the way you would if you were paying $160,000 a year for the privilege, then you are setting yourself up for a glorious future.

The key is what comes after. With the skills you learn from these e-books, you'll have everything you need to step it up at your current job, start a killer little side hustle, or even begin your own company and start acquiring your own customers.

You could spend money to learn the theory behind making money. Or you can just make money. Take your pick.