Many products have a UPC bar code that can be scanned into a computer database which is regularly updated to reflect price changes.
Most stores require scanning every product first and feeding this data into a database which takes into account inventory levels to then update prices. From there, a rolodex of pricing labels are created which then need to be manually placed under the products on the shelves. This is inherently tedious and inefficient.
I have a Prototype for a UPC/Pricing Label Scanner and Printing Gun which has its own database of products, inventory levels, and prices built into it. Simply scan the UPC and it will create a label which can be applied via an adhesive backing.