I have something very similar somewhere in my project graveyard. I never got round to launching but your comment has motivated me a little. I'll see if I can dig it out.
I don't think it really matters what you sell, especially in this case where you just want to improve your sales technique. The main thing is that you sell an experience, not a product.
Such a shame. That will rule it out for a lot of developers.
For all your designers and front-end developers: there is a real need for something like this. Have a look through the weekendhacker archives and look at how many developers ask for design help. Templates on sites like themeforest are often only suitable for basic crud/admin apps or require so much customisation it's easier to start from scratch. At the other end of the scale you have a variety of frameworks and boilerplates which are great from a technical perspective but do little to help aesthetically challenged developers like me.
What we need is something in between. A library of pre-styled css 'components' that look good and support the most significant browsers. Similar in principle to Nicole Sullivan's OOCSS but with a greater range of visual styles. I'd pay significantly more than the cost of a themeforest template for a component library that managed all the cross browser issues for me and I'm sure others would too.