Considering the very high cost of setting up a Cloud that is anywhere remotely near 'acceptable' for a large scale deployment, you can do what we do. We simply control our own dedicated/private Cloud which we rent. Meanwhile, we're busting our butts to grow and expand, creating a very positive track record which will help us financially in the future to deploy our own AppLogic build.
Unless you have a VERY large budget to do it right, I wouldn't both building/deploying your own Cloud from the start. Do what we do, purchase a dedicated/private cloud resources from another provider, grow your business until you have a good enough track record and general interest to invest into your own deployment/build, and then go from there. Any reasonable provider will allow you to create/destroy/scale VMs instantly, this means you can offer Shared hosting on a VM, Reseller on another, sell Cloud VPSes, etc.
Feel free to PM me with any questions.