Price Trends for Local Networking Equipment a 2003 paper from the Federal Reserve.
A Brief History of the Internet discusses some of the market dynamics in networking.
An article focused on The Early History of the Internet from Elon University.
The History of Lans explains product development for the networking market
Network Technologies from the Internation Journal of High Performance Computer Applications, explains some technology and market considerations.
The spreadsheet below contains historical price per megabit in dollars for ethernet network interface cards, starting at 10 Mbps.

Networking Prices