Below you will find a few of helpfull links.
Steinway & Sons - American and German manufacturer of handmade pianos, and subcontracted pianos from suppliers sold under secondary names.
Bosendorfer - one of the oldest piano manufacturers, was established in 1828 in Vienna by Ignaz Bösendorfer.
C. Bechstein Pianofortefabrik AG (also known as Bechstein) is a German manufacturer of pianos, established in 1853 by Carl Bechstein.
Renner - Die Firma Louis Renner GmbH & Co. KG in Deutschland gilt weltweit als der angesehenste und renommierteste Hersteller von Klaviermechaniken.
B. & K. Baumagartel GmbH - B.&K.BAUMGÄRTEL GmbH, based in Gera-Langenberg in Thuringia, is a supplier of parts for upright pianos, grand pianos and historical keyboard instruments, tools, transport equipment, etc.
Piano World - Home of the world famous piano forums. The most complete resource for piano information on the web.
Blue Book of Pianos - The "Bluebook of Pianos" has been published for over 45 years. You may only buy or sell one piano in your lifetime. This guide should answer your questions.
PianoMart.com - buy or sell your piano