White truffle season is ongoing in Italy in October and November. Concurrently, there is a famous charity auction of white truffle "lots." Bidders from around the world jockey for the prize of the biggest, best white truffles of the season. Prices can be incredible, in the hundreds of thousands of US dollars. One auction lot in the past sold for $6,250 per ounce. That equates to some $500 per slice! A plate of simple tagliatelli and white truffles would have to sell for $3,000 to break even. This is not food for mere mortals.
From Wikipedia:
"The "white truffle" or "trifola d'Alba Madonna" ("Truffle of the White Mother" in Italian) (Tuber magnatum) is found mainly in the Langhe and Montferrat areas of the Piedmont region in northern Italy and, most famously, in the countryside around the cities of Alba and Asti; Acqualagna, in the northern part of Le Marche near Urbino, is another renowned center for the production and commercialization of white truffles and the annual festival is one of the most important in Italy. White truffle can also be found in Molise, Abruzzo and in the hills around San Miniato, in Tuscany. It is also found on the Istria peninsula, in Croatia in the Motovun forest along the Mirna river, and in Slovenia along the Dragonja and Rizana river, as well as in the Drome area in France. Growing symbiotically with oak, hazel, poplar and beech and fruiting in autumn, they can reach 12 cm (5 in) diameter and 500 g, though are usually much smaller. The flesh is pale cream or brown with white marbling. Italian white truffles are very highly esteemed and are the most valuable on the market: The white truffle market in Alba is busiest in the months of October and November when the Fiera del Tartufo (truffle fair) takes place. In 2001, the Tuber magnatum truffles sold for between $1000–$2200 per pound ($2000–$4500 per kg); as of December 2009 they were being sold at $14,203.50 per kilogram.
In 1999, one of the largest truffles in the world was found near Buje, Croatia. The truffle weighed 1.31 kilograms (2 lb 14 oz) and has entered the Guinness Book of Records.
The record price paid for a single white truffle was set in December 2007, when Macau casino owner Stanley Ho paid $330,000 (£165,000) for a specimen weighing 1.5 kilograms (3.3 lb), discovered by Luciano Savini and his dog Rocco. One of the largest truffles found in decades, it was unearthed near Pisa, Italy, and sold at an auction held simultaneously in Macau, Hong Kong, and Florence. This record was then matched on November 27, 2010 when Ho again paid $330,000 for a pair of white truffles, including one weighing nearly a kilogram.
In December 2014, a White Alba’s Truffle weighing in at 4.16 pounds or 1.89 kilos was unearthed in the Umbrian region of Italy by the Balestra Family of Sabatino. It was auctioned at Sotheby’s in New York. While some had expected it to sell for $1 million, it was sold for $61,000 to a Taiwanese buyer.
A variety of white truffle (Tuber magnatum pico) is found in other parts of northern and central Italy, but is not as aromatic as those from Piedmont."