I have a friend that is the city manager of a town of about 25,000 where his main task is processing requests for building permits. Actually a volunteer-type job, no salary. But he makes a bunch of contacts every day, and his address book is huge. So he is busy all year except the Holidays. To fill in this time he started a Christmas tree lighting service (houses, lawn ornaments, etc.). In this 3-month period he makes enough to keep him going the rest of the year.
When one of your customers makes a purchase, you purchase the product from a third-party company (the drop shipper, usually a manufacturer or wholesaler) for a lower price. This process is as simple as forwarding the order from your customer, a process that can actually be completely automated. (Remember you don't have any risk here of buying inventory because the sale has already been made).
Pay-per-click advertising is the easiest way to get traffic to a brand-new site. It has two advantages over waiting for the traffic to come to you organically. First, PPC ads show up on the search pages immediately, and second, PPC ads allow you to test different keywords, as well as headlines, prices and selling approaches. Not only do you get immediate traffic, but you can also use PPC ads to discover your best, highest-converting keywords. Then you can distribute the keywords throughout your site in your copy and code, which will help your rankings in the organic search results.