website that sells (pre-designed - customize your own website with custom cms)

I want a site that sells websites to service businesses... (several standard templates to choose) (customer can access - EASY - customized CMS panel and edit website) I am a designer & will be doing the design of the site elements.. eg: banner / pictures and putting it together for my customers.. So for example: I get a customer for a plumbing business and he chooses (standard template 3) - I will design a header/banner for him, upload pictures for him and upload or design his logo...change background to suit his brand.. then if he wants to add in his own content later -he can with custom cms panel which is very easy to understand.. I will also be hosting site for him... Please supply me with the best solution you have for me... please take into consideration this is a start up an budget is limited. I want to save money where I can, if I must design templates myself?