Recently I wrote small app utilizing handheld scanner
WelchAllyn : Imageteam 3800 (Hand Held Linear Image), Model # IT3800

As David says, this is like another keyboard. You plug it in keyboard port in parallel with existing keyboard and it is functional right away. Open Notepad, Word or position cursor on a TextBox field in FoxPro form and scan a pop drink :) -- you'll get it typed in immediately.

The scanner I mentioned above understands several barcode standards. Works very well with my FoxPro app. The price is about 200-300 CAD. Should be many other models around with very similar functionality, not just this one of course.