Question
I already have a website and want to add a store to it. I am looking at Shop Site, Volusion, Big Commerce & Shopify. I have limited tech knowledge on how these work. Things that are important to me are tech support, ease of use, shipping, cost and keeping people on my site rather than taking there somewhere else. Any feedback regarding these woyuld be appreciated
Answer
You mentioned you already have a website. What are you using for your existing website?
If you're using WordPress already for your site you could use WooCommerce. It's a plugin for WordPress so it seamlessly integrates into your site. It's bigger than all of the other platforms out there (Shopify, Magento, BigCommerce, etc) and has a ton of integrations.
If you find WordPress confusing or you don't already have it setup then looking into Shopify would be next best course of action.
I hope that helps! :)