Before I answer that question, I will explain this illustration for you:
You buy reseller hosting plan 4 with us and cost about $660/yr, with those plan you will get 200GB disk space, 600GB bandwidth, 40 websites, 20 MSSQL 2008 DB, unlimited domain and subdomain pointing.
Configure your reseller to several plans and it depends on your target market. Make 3 plans or more with aiming low and middle segment. Plan 1 = $5, Plan 2 = $10, Plan 3 = $15.
Sell the three different plan to the market and make your revenue. The cheaper plan will get more customers compare to the expensive one.
Your Profit = Total Revenue - Total Cost.
The cost includes hosting fee and WHMCS billing system. And at the end of year you will get net profit $1533.6/yr.
The illustration above does not include revenue from selling domain name, selling SSL Certificates, and selling addons. You can easily resell our addons and make money from it. For eg, you can resell MS SQL 2008 Addon with price $7/month and you earn profit of $2/month. There are so many addons you can resell such as Website Addon, FTP Addon, Sharepoint Addon and much more. You can also make more money by resell "Reseller Plan"
* this illustration may vary from actual condition