Photo Downloads

Hi

I’m thinking about building a website for photographers where they can sign-up and upload images to their portfolio for people to purchase online. It has to be searchable and pretty much self-running (once everything is set up ofcourse). I’m wanting to make it using MX and most likey I’ll have to use PHP at some point, but just wanted to know the how I would go about building something like that…Any ideas where I start?