How much does implementation of an RF ID and Barcode systems cost?

How much does implementation of an RF ID and Barcode systems cost?
what are their relative merits and demerits?

Best answer:

Scientific American had a good article on RFID a couple of years ago. I believe they said that RFID was down to about $.20/tag at that time for stores like Walmart that sell millions of items, and that the goal was to bring it under $.05/tag.