I’m all for seeing some Umbraco add-on’s but unfortunately the structure does not lend itself to templates. I’m sure you know what I’m referring to, the system has almost no default design or content structures, allowing you to define them yourself. This is a huge part of the power behind Umbraco as it’s completely configurable to your specific needs, however that flexible architecture is also the reason you can’t turn on/off any design you want the way you can with WordPress.
If someone designed a good content framework for Umbraco first, similar to what the “Creative Website Starter (CWS)” does, then you would have an established set of standards for themes to tie into and you would be more able to create design templates. Right now I don’t know of anything other than CWS that makes this possible. It sounds like a package waiting to be written if you ask me.
Packages are a different story. You could easily sell those on CodeCanyon.