If you are just going to put up a website, then I might agree with "Tunes", but it really depends on what you want to do.
You really need to define your niche. It doesn't sound like you have a handle on it yet, just an idea. You should narrow it down so that you know EXACTLY who you are targeting.
If you want any graphics for your site, or things like an e-book, then either you will need to do them (if you know how), or you will need someone else to do them. You can get these done fairly cheap, but you might want to figure in another $10+ per graphic.
You will also need to have content and copy.
Of course, if you don't know your niche, you won't know what you should be selling.
Once you know what you will be selling, then you will need to have content for your web site/blog.
Then you need copy for your sales page.
Either you will need to do the writing, or you will need someone who understands how to write sales material. This adds more dollars to your bill.
You can begin with a few affiliate offerings so that you don't need to even have that website, or sales copy.
If you are going to use Social Media, then just put people in touch with the affiliate offer.
There is one problem with doing things that way, and that is if you only send people to offers, then they will stop clicking on your links.
So, the best thing to do is to get a domain, set up your site, put some nicely written content on the site/blog, and send people to your blog where you can have an affiliate link.
Meanwhile, you can learn about writing sales copy, and can even occasionally send people directly to your affiliate offer.
By the way, think about collecting some email addresses so that you can build up a relationship with a few people. These folks are your most likely buyers.
You will need an autoresponder, and that will add another 20+ dollars a month, but it is well worth the cost.
Working online is still way less expensive than doing most anything in the offline world.
Good Luck!
