The term "ninja sword" can refer to various types of swords associated with the historical ninja warriors of Japan. The most commonly known ninja sword is the ninjatō, which is often depicted as a straight, single-edged sword with a square guard.

The price range for a real ninja sword can vary depending on factors such as the quality, materials used, craftsmanship, and historical significance. It's important to note that there is limited historical evidence of specific swords exclusively associated with ninjas, as they primarily used common weapons of their time.

If you're looking for a modern reproduction or a functional ninja-style sword made by contemporary swordsmiths, the price can range from a couple of hundred dollars to several thousand dollars. However, the historical accuracy and authenticity of these swords may vary.

It's advisable to research and consult with reputable sword dealers or experts to ensure you are getting a quality product that aligns with your budget and preferences.