I've built and sold a few products over the years, but just started to get really heavy into it. It is definitely one of the most lucrative ways to earn money online if done correctly. When Clickbank was young, I remember re-hashing some ebook for winning at poker. I paid the $50 to get the product reviewed, got it listed, then forgot about it. I logged into my CB account a month later and there was over $1k in my account!
That was during the eBook craze. Today with better technologies like stronger computers, and and better average consumer bandwidth, info products have gone more elaborate using multi-media. Developers will take their original content, like articles, ebooks or whatever, and convert the information into different mediums, adding it to the product. One product might have: An ebook, a video series, email series, and an audio file making it look like a complete course. It's easy to do this sort of thing, and yes, your presentation is everything. Do not let people tell you that shitty looking sites, and graphics will let you bank.
Going on what Darren9682 said, yes there are your so-called guru's that appear to sell their products like there is no tomorrow, but do not let this discourage you. There is plenty of room for growth in this sector, believe me.
My first real product is in pre-launch. I already have 25 affiliates sign up to promote it. I've managed to have 83 people opt-in to be stay informed of the launch. That does not sound like much but in the 25 that are ready to push my product, I recognize like 12 of them to be super affiliates. All this before the launch, and I'm a nobody. Fresh on the scene. Is it a tight knit group of so-called guru's? Of course it is, but use that to your advantage. Most of those guru's are good at nothing else besides selling their product by getting you hyped up in their motivational presentations. Buy their product, and apply their "teachings". Did they work for you? Do you think that if it didn't work like it was advertised, would that consumer buy from that vendor again? Highly unlikely. That is where I come in. I've been in IM since like 1999 in one way or another. I know what works. I will if I have to, but I would rather not sell to the noob. I would rather sell to people that are slightly past this level, and are already frustrated with the hype. Occasionally some of these guru's will have some info worth anything, but it's usually methods that I think they base on theory. That is cool if it gets my wheels turning.
If your not a complete noob, you will most likely know your way a little around Wordpress. It's only the biggest CMS on the planet. For me, Wordpress is like an old friend that's never abandoned. She makes me money, and I feel warm. I only felt right getting serious with developing a product if it revolved around my gal, so that is what I did. I had a theory about how to get your audience to pay more attention to your sites advertising. I paid a developer from Odesk to code me a plugin that would do what I wanted it to. It was crude when finished, but it worked. I got much more ad interaction on my site. I tested it with my friends on their sites. We all got the same results. So I got the plugin fully developed and that was my product. The best thing about it is that I already have the next 3-5 years worth of new features already thought up. It all worked out perfect because it is a strong and functional base, that can be expanded by new features meaning new revenue avenues. Different models could be worked into it including making it subscription member base.
My point is, don't let those puffed up "guru's" discourage you. There's tons of more valuable information available for free here on this forum than in all of their products combined. If anybody is thinking about networking on product development/marketing, let me know. Maybe a skype group or something. I have some knowledge on this subject, and I'm sure others do too. It would be great for us get together and share ideas, or maybe even JV.
The purpose of this post wasn't so I could self-promote, but if there are any affiliate marketers reading this thread that want to check out my product, shoot me a PM.