The value of pianos can vary widely depending on factors such as age, condition, brand, model, historical significance, and provenance. Here are some examples of pianos that have achieved significant value:

1. Steinway & Sons Model D: Steinway & Sons is renowned for producing some of the highest quality pianos in the world, and their Model D concert grand piano is particularly sought after. These pianos are prized for their exceptional craftsmanship, rich sound, and versatility. Customized or limited edition Steinway pianos, especially those with historical significance or celebrity ownership, can command high prices at auctions or private sales.
2. Bösendorfer Imperial Grand: Bösendorfer is another esteemed piano manufacturer known for its exceptional instruments. The Bösendorfer Imperial Grand is one of the largest and most prestigious concert grand pianos available, featuring 97 keys instead of the standard 88. These pianos are prized for their luxurious craftsmanship, exquisite sound quality, and rarity, making them highly sought after by collectors and performers.
3. Fazioli F308 Concert Grand: Fazioli is a relatively young but highly regarded Italian piano maker known for producing exquisite handcrafted instruments. The Fazioli F308 is one of their flagship models, renowned for its exceptional tone, dynamic range, and responsiveness. These pianos are prized for their rarity, as each Fazioli piano is meticulously crafted by hand in limited quantities.
4. Blüthner Model 1 Concert Grand: Blüthner is a German piano manufacturer with a long history of producing high-quality instruments. The Blüthner Model 1 concert grand piano is renowned for its warm, rich tone and exceptional craftsmanship. These pianos are prized for their historical significance and association with renowned composers and performers throughout the years.
5. Erard Grand Pianos: Pianos made by Erard, a historic French piano manufacturer, are highly valued for their craftsmanship and historical significance. Erard pianos were favored by many notable composers and musicians, including Frédéric Chopin and Franz Liszt. Antique Erard grand pianos from the 19th century, particularly those in good condition with original features, can command high prices among collectors.

These are just a few examples of some of the most valuable pianos, but there are many other factors that can influence the value of a piano, including its condition, rarity, and historical provenance. Ultimately, the value of a piano is subjective and can vary depending on individual preferences and the current market demand.