The materials are there to facilitate the learning of certain skill. And there are many ways to achieve it. I believe if you are a homeschool mom/dad you don't need all the Montessori materials available to successfully homeschool using the Montessori Method.
Maria Montessori created the method with the school environment in mind and not for homeschoolers (let me know if I am wrong). The classrooms were full of children. Therefore, they needed all those hands on materials to keep everybody busy learning let say. But at home it is different. There are not so many children and you don't need all the materials at once. There are a lot of materials you can make yourself if you can, or find a way to teach that particular skill the Montessori way.
You could use the method 100% or you can pick and choose what your child likes from various different approaches and still help your child learn that certain skill. So, for home learning I think the best you can do is to get the prepared environment at home to suite your child's needs. This is especially important for young children to foster their sense of autonomy and belonging.
Remember that the Montessori method is not only a method and it is not only the materials but a way of life.