The part of beef that is most expensive is the Japanese A5 Wagyu, especially the authentic Kobe beef as a result of their intense and even marbling of fat content, that comes from genetically superior cattle, which results in a rich umami flavor and melt in your mouth texture.
Japanese A5 Wagyu often costs hundreds of dollars per lb, and Filet Mignon s also a part of a cow that is another most expensive part of a cow.
Filet Mignon is also pricey for it's tenderness but less tender and less pricey than top tier Wagyu.
The factors that drive the cost up for Japanese Wagyu are Wagyu genetics, Kobe Certification, A5 Grade and Location and rarity.
Japanese Cattle breeds naturally produce more intramuscular fat, which creates incredible marbling.
Authentic Kobe is also a specific type of Wagyu from the Hyogo Prefecture and is raised under strict standards, which makes it exceptionally rare and costly.
The highest Japanese grading of A5 also signifies the best marbling, color and texture, which commands the premium prices.
And Kobe beef is more expensive the further you get from Japan, and rare breeds and specific farms like Mogami add to the price as well.
A5 Japanese Wagyu and Kobe Mogami is the pinnacle of bee that is known for it's buttery and intensely marbled fat, rich flavor and tender texture that is often priced at $300.00 lb to $800.00 lb and sometimes more.
Filet Mignon and Tenderloin are extremely tender as they come from a less worked muscle, which makes it a luxury cut of meat from the cow, although it's usually less expensive than A5 Wagyu beef.