Here is a constantly changing list of the most valuable German stamps and overprints with proofs of sale. The list includes old states, but doesn’t colonies and occupied territories.
1.$16,100.00, Saxony. July 2007, Cherrystone auction. German States – Saxony. 1851 1/2ng black on pale blue paper, printed in error (paper color on 2ng, rather than the gray color of the 1/2ng), Rismondo cert. (Mi. 3F, Scott 3a, cat. €25,000)
2. $12,075.00, Germany. May 2007, Cherrystone auction. 1901 3pf on right half of 5pf green, Vineta Provisional, lightly hinged, cat. €13,000.
3. $6,612.00, Saxony. May 2007, Cherrystone auction. German States – Saxony.