Depending on the network, you may also need to pay setup costs. This covers the cost of integrating you to the network and testing tracking etc. Start-up fees can range from nothing to over $5,000. I have been asked for $30,000 before and, obviously, I never started with that network. This cost is often negotiable when you discuss contracts with the network, but it is worth noting when considering the start-up costs.
Your small business must pay state income tax in the state you operate in. Depending on how your business is organized, you could pay corporate tax or a limited liability company tax in addition to your personal income tax. You may pay taxes in the state the selling company is located in if that state taxes entities who earn money within their borders (even if the earner is located out of state). Your affiliate marketing company is considered a separate entity from the selling company when it comes to figuring state income taxes.