The price of a real katana from Japan can vary significantly depending on several factors, including the craftsmanship, quality, age, condition, historical significance, and reputation of the swordsmith. Additionally, factors such as the materials used, construction techniques, and any accompanying certificates of authenticity can also impact the price.

Authentic, high-quality katana swords that are made by renowned swordsmiths or belong to historical periods can be quite expensive and can range from several thousand dollars to tens or even hundreds of thousands of dollars. These swords often hold significant cultural and historical value, and their prices can reflect their rarity and craftsmanship.

However, it's important to be cautious when purchasing a katana, as there are also many replicas, reproductions, and low-quality imitations on the market. These replicas may be more affordable, but they may not possess the same level of craftsmanship, historical significance, or value as an authentic, traditional Japanese katana.

If you are considering purchasing a real katana from Japan, it is advisable to seek reputable dealers or consult with experts and collectors in the field of Japanese swords. They can guide you in evaluating the quality, authenticity, and value of the sword you are interested in acquiring.