I believe their look is what attracts people to them. They have different leaf shapes and colors as does anubias. Some of the buces even have a really nice blue shine or white speckled look to them that you would be hard pressed to find in any reasonably priced anubias. In my opinion its all about how they look the price is just based on how rare they are in the hobby. And the price is going down as they become more commonly seen.