Some stores, like Costco, have an interesting, alternative approach. Many items in their electronics department are prepay. You can try out the floor model (tethered to the display platform), and if you wish to purchase it you pull a cardboard item card. That card is scanned during the checkout process, and once payment is received, the staff bring the physical item from secure storage to the post-paid customer.

With the item card approach, you never have the product in your hands until it has been paid for. Between that practice and their receipt checking at the exit, I do wonder what their theft numbers look like.