Sources of historical data and information for computer processors
The Chronology of Microprocessors managed by Ken Polson has pricing, technology, and historical details of development beginning in 1958.

Intel's Microproccesor Quick Reference guide provides a chronology of technical information such as the number of transistors beginning in 1971. 
A Microprocessor History maintained by Dr. Sandra Wooley at the University of Birmingham provides some price information and a detailed product development history.
The CPU Shack Museum provides a large variety of data on Intel and AMD microprocessors.
The History of Microprocessors contains a lot of historical development information and some information on pricing

The spreadsheet below provides historical data for the best price per transistor each year, about mid-year.

Processor Prices