The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.
#2 High Priced. Another downside is that the course does cost more, a lot more. At $997 it does sound like a lot but I prefer not to look at the cost as a burden but rather an investment in my future. The way I see it if this teaches me how to how to build even a modest income of a $1000 per month for the rest of my life I feel the price is well worth it.
You can put up banners on your site, to promote your affiliate offers. Most affiliate programs will usually provide their own creatives when you sign up for their offers. All you have to do is insert the banner on a highly trafficked page (your affiliate tracking is usually embedded within the code). Banner ads in the right locations can do a great job of driving sales.
When promoting affiliate offers, just make sure you are fully aware of all the terms and conditions attached to your affiliate program. Some programs can be strict about how they allow you to promote their products. For example, some may limit you to banner ads and links only, while others will allow you to use paid advertising, but won't allow email marketing.