USB scanners exist (I believe PS2 is the odd one these days).
Avoid the 'Flood" (hold the scan head against the bar code) style. It is bin bait in any bright light situation.
The one I have is really old Pro model (Symbol 4004 that I am too cheap to buy the USB cord), so I now use a PS2->USB Keyboard-mouse adapter.
This rig works perfect for
add from ISBN as there is only 1 field. You Tab (or mouse) to OK when ready.