Square revolutionized the idea of a mobile POS solution for the "everyday Joe" (or Jane) at a time when POS solutions usually costs well over the thousands of dollars. Since then, Paypal, Shopify, Clover, Intuit and Microsoft have all come out with competing solutions because the number of small businesses and startups is only increasing every year.
The issue for Best Buy is they only carry the Stands and/or the standalone chip/NFC readers. If someone wants a complete solution, such as the cash drawers, barcode scanners, receipt printers, etc. You're sending that business online and to give you an idea, it's the difference between a $169.99 sale (for package with Stand & EMV/NFC reader) versus over $750 for the cash drawer, barcode scanner and receipt printer with the Square Stand.
That being said, pricing for the component (Stand with NFC/EMV) that Best Buy DOES carry is the same, which rolls out the red carpet for someone to just go online and buy everything together from Square. The other opportunity here is to create a bundle where if someone buys all the Square stuff and an iPad there's a savings. It doesn't have to be significant, but if you think about the revenue that would be generated just by a 10 or 15 percent increase in FULL solution purchases (all components plus iPad) from Best Buy that would be pretty substantial.
The most requested accessories (for your reference) are the cash drawer, barcode scanner, (wired) printer -- because there is a bluetooth one as well and the receipt paper rolls.