There's several other resellers out here. And while I can't speak to pricing, one recommendation I would make is to give each of you clients their own Azure subscription. This allows you to easily take charges and pass them back to the consumers with whatever
mark-up you feel is necessary. Just be sure to read the usage rights of subscriptionsr required via the cloud essential program.
An if you were thinking about hosting all your clients on a single subscription, keep in mind this wil require you attempting to work wiht MSFT to try and get the maximum number of hosted services as well as potentially the maximum number of cores increased.
The current limits (6 services and 25 cores) will likely impose some constraints.