AHA! That didn't take much time at all. I remembered that it was a huge ripoff of Delicious Library for Mac (hey, if they don't want to make a Windows version, someone else will fill the gap). So after a simple search on Alternativeto.net I remembered the software I used was
Mediaman.
I'm not sure what the software is like now, but it worked pretty well three or four years ago when I last used it. I just got out of the habit of scanning the info in.
*edit*
I just tried the webcam barcode scanning in Mediaman, and it worked really well, so definitely give it a try. You might need a decent webcam to get the detail necessary for the capture, but it should make the process of entering all those books fly by much faster.
*edit*
Sorry, I just noticed that the purchase price is double the top range you specified. Fortunately there's a free trial, and that should show you how fast it is to import the information into the software. It's as fast as holding the item's barcode up to a webcam. If you set up the physical scanning station correctly, you could really sail through the process.