Hi,
I think you'll find that it's not the scanner hardware that makes a difference, it's the software. There are many other packages out there, from < $100 to many thousands. The software that is packaged with any scanner is an inexpensive compromise; if you really want to do this, you need a good quality tool. Many people don't do this with their scanner, if the manufacturers included better software, they would just be pricing themselves out of the market!
The key is to find a product that works well on your originals. Exact fonts, print sizes, paper type, color, all make a big difference on how well this works.
If you seek out publications about desktop publishing, etc. you can find many product reviews that will put you in the right direction, after that, insist on a demo, so that you can see what it will do in your environment. good luck.
p.s. I've used some products from Caere (now ScanSoft) with success, we currently use a Toshiba product that's sold as a system with their digital copiers. Of course, in your environment, your mileage may vary!
---Will