I need a Shopping Cart and integration with Authorize.Net

I need a shopping cart built for my website. I have all of my products and website complete, But i need you to install a shopping cart with all of my products and integrate with [login to view URL], I dont have much money, so im hoping somebody already has the code for this, and can just do a script installation for 50 dollars. YOU MUST PROVE TO ME 2 THINGS 1. THAT YOU CAN COMPLETE THIS TASK PROFESSIONALLY 2. THAT YOU WILL BE ABLE TO FINISH THE JOB WITHIN 48 HOURS (2 days).