I was in the same situation as you and after days of research I settled on the Rich WP affiliate theme. It is great and is easy enough to use once you learn what each menu item does. It can be daunting at the start but I don't know my HTML from my CSS or my PHP and I have managed to put together some decent looking websites. You just need to set up a site to play with and start clicking things and see what changes!
You do receive an installation manual, a large number of templates and the support from Felix is second to none. No matter what your enquiry he is only to happy to help and always within a few hours.
If you search the web you'll find a discount voucher for the theme I am sure.
I would say go for it, it will allow you to become familiar with one theme which you can then use to create as many websites as you wish in super-quick time.