Thanks for reaching out and posting this question!
You can absolutely purchase the scanner from a third-party retailer, such as Amazon, or directly from Socket, and we do indicate this on our guide - Supported POS hardware. This guide also contains a list of supported hardware models for the mPOPs (all-in-one), cash drawers, barcode scanners, barcode printers, receipt printers, and iPad stands, which should come in handy when you’re shopping around. However. it’s important to note that some iPad stands (eg. Shopify Retail Stand for iPad) and card readers can only be purchased through the Shopify Hardware Store.
I’d love to hear more about your business! What kinds of products are you selling? Do you have a marketing plan prepared for your store?