Sean hit the nail on the head. You MUST be able to offer the Value Added options. You have to be creative enough to mark up your pricing and offer features that the other companies do not offer - otherwise people just directly to the source.
For many people, being an affiliate of companies that offer recurring comission is more beneficial. This way you send the customer directly to the hosting company and you get a percentage while the customer is their client.
Being a reseller yourself means that you must be available to your customers. You'll need to invest in a pager and be on call 24x7 while things fail and you fix them and answer your customers questions as needed.
I'm a big fan of affiliate type setups. Too many resellers startup, offer rock bottom prices and then don't have enough to cover expenses and time needed to operate the business.