E-commerce website for downlodable media content

Hello all!
I have operated e-commerce website for downloadable media content for over 6 years. All through the time I have used e-commerce script solutions which was not catered largely for the downloadable media content, where you would have a robust media preview, single or all track selection and better download options.

So now I am at a point i need to move on to next phase of the shop to stay in the game for new age websites with all the bells and whistles! :x
I have spent tons of time to see what are the paid options for such features. And sadly I have not come across any paid solution (excluding the hosted solutions) that covers all the basis needs of a downloadable media site.
I have looked in to some of the established e-commerce music sites, such as:

and I began to wonder do they all develop website independently, if so what about these less-known sites:
how do they come about having all the options required.

Lastly, I wonder if anyone knows of such paid script that would give a feeling of an mp3 music stores without having to build one from the scratch. One would think with so many less-known-mp3-music-portals around there would be a paid solution which can be of current age, which are not available in most of the high-end-paid-ecommerce-solutions. :rolleyes:

Thanks for reading and please guide me if you been enlightened! :slight_smile: