Add Ecommerce Store Front to Local Shop Website

Hello, Last worker i awarded this project to wasted 8 days and got nothing done, so please only bid if you are able to start work immediately, and make sure your time needed for completion is accurate!!!! we are a local paintball shop. our website is danburyactionsports.com. I built the website myself, and have tried adding a plugin for the online store but had issues. We would like a ecommerce storefront added to our website so that we can post items, price, images, quanties, etc. We would like to USPS as our shipping method with instant shipping calculation. We would like to use PayPal is our payment method. We currently accept credit cards through Mercury Payment Systems and our current point-of-sales system is Microsoft Dynamics, in case those can be integrated as well (Mercury for accepting CC payments and Dynamics for inventory). Also interested in some SEO and maybe general work on our website too, please post your specific ideas. Only looking to spend about $50 for the storefront (as we will be adding items and doing most of the work ourselves) and maybe another $50 (maybe a little more) for other site work.