Consider the average cost of the NSFNET backbone in 1993: about $10^6 per month, for about 60,000 * 10^6 packets per month. This implies a cost per packet (around 200 bytes) of about 1/600 cents. If there are 20 million users of the NSFNET backbone (10 per host computer), then full cost recovery of the NSFNET subsidy would imply an average monthly bill of about $0.08 per person. If we accept the estimate that the total cost of the U.S. portion of the Internet is about 10 times the NSFNET subsidy, we come up with 50 cents per person per month for full cost recovery. The revenue from congestion fees would presumably be significantly less than this amount.
The average cost of the Internet is so small today because the technology is so efficient: the packet-switching technology allows for very cost-effective use of existing lines and switches. If everyone only sent ASCII email, there would probably never be congestion problems on the Internet. However, new applications are creating huge demands for additional bandwidth. A video e-mail message could easily use 10^4 more bits than a plain text ASCII e-mail with the ``same'' information content and providing this amount of incremental bandwidth could be quite expensive. Well-designed congestion prices would not charge everyone the average cost of this incremental bandwidth, but instead charge those users whose demands create the congestion and need for additional capacity.