I need a website built…

I wanna built a beat selling platform where artist can sign up create a page and sell beats off the platform…for example they have beatstars and airbit for producers to sell beats off of…But i wanna make my own platform…How does this work?? Script?? theme?? all i have is wordpress and hostgator baby package (unlimited sites) But Im willing to pay someone to build this site…not the GFX part as I do my own graphics and design…I just need the platform….