I have been researching on open source software for an online grocery shop project. I have now narrowed by search to .NET based nopCommerce and the PHP based PrestaShop shopping carts. My plan is to acquire an open source shopping cart and hire a local developer to customize it to our local needs & as per our requirement. I'm now wondering whether I should have a developer start the whole project from scratch, or use an open source software such us PrestaShop or nopCommerce which can then be customized? Note that my store will have thousands of products and services so I want something that can handle up to 5000 products and over. Thanks for your thoughts and advice in advance.