I would highly recommend buying a used Metrologic or Datalogic handheld scanner at or above $50, it'll work a lot better and (if programmed) can usually handle 2D barcodes. This is the major reason you see Fred Meyers spending $5k a pop on new Datalogic 9800i's, and why Walmart had the NCR 7878 custom built for them, scanning performance is a make it or break it deal.
On the Pi side, I'd sub in a OrangePi Plus 2E since it has 16GB of eMMC and has a fully libre stack now at a lower cost, and would likely nab a used monitor for $10 locally rather than pay for a low res 7" at a premium price.