Buying a cheap pyramid is possible these days; however, we have to keep in mind that a pyramid is a device, an apparatus that can produce harm if it's misused.
What makes a pyramid work?
Many factors involve the functioning of a pyramid; A very important one, apart from being well oriented to the magnetic north, is the density. Density is the relation between the size and weight of the pyramid.
For example, a pyramid made out of copper pipes with one inch of diameter, with a square base of 50x50cm will have enough density to "close" its field, therefore, producing a pyramid effect; But if we use the same diameter of copper pipes to make a pyramid with a base of 200x200cm it won't have enough density, so you are pretty much buying a pile of copper pipes. In this case, we have to find a greater diameter of copper pipes to reach enough density. However, the use of copper is not recommended for living beings because it is a diamagnetic material. Diamagnetic materials are slightly repelled by magnets (we are working with magnetism here); their particles make an opposition force.
What is the right material to build a pyramid?
As I mentioned above, a pyramid is a device, a multifunctional device, so depending on the function, we can determine the best material for that function.
Piramicasa and the club Osiris specialize in therapeutic Pyramids, therefore Paramagnetic materials. Its atoms align with the magnetic field particles and return to their original position when not affected by such a field.
Paramagnetic materials can be used alone or combined. Piramicasa manufactures only high-purity aluminum pyramids, manufactures on demand, the prices variates from shipping costs, custom aluminum cost at the moment of the order, etc. Like everything, once the demand increases, the prices decrease.
Now, you could use wood but consider the "density," depending on the wood, it needs to be about ten times heavier than our aluminum to produce the same effect on the same size pyramid.