Kepler understood that the heliocentric model of Copernicus was not enough. The demonstration proposed by Copernicus is admirable but is indeed nothing more than a calculation.
Kepler had a poor eyesight and was not himself an astronomer. He joined the team of Tycho Brahe in Prague. Kepler used the highly accurate observations made by Brahe while opposing his planetary system that did not explain the orbit of Mars. His own work led him to demonstrate that the orbit of a planet is not circular but elliptical.
He now sees the sun as a motor that generates a greater speed when the planet is closer and compares this effect to a magnet. Newton will rely directly on Kepler's results to formulate the law of universal gravitation.
Kepler prepares from 1600 to 1606 the presentation of his first two laws. A dispute with Brahe's heirs suspends the publication until 1609. The title, Astronomia nova, shows Kepler's rightful ambition to offer a completely new approach in this domain. Astrophysics was indeed born with this book.
The printed quantity is very small : the author is an employee of the Emperor Rudolph II and the edition is done without a commercial intent. To compensate for some salary delays, Kepler obtains the right to sell a few copies.
A copy of Astronomia Nova which belonged to the Royal Institution of Great Britain is estimated £ 90K for sale by Christie's in London on December 1, lot 245.
Here are two recent results on other copies : £ 212K including premium by Sotheby's on May 20, 2014, and $ 230K including premium by Christie's on June 17, 2008.
SOLD for £ 146K including premium