The decision as to who will or should purchase the materials for your remodel will probably be a matter of price and convenience.

You might choose to have your contractor purchase materials because it is more convenient or because s/he can get better prices. On the other hand, if you enjoy shopping and you have the time to spend comparing prices you might prefer doing the buying. Shopping sales, searching for the exact piece that will be perfect, takes time.

The other consideration in making the purchases is arranging delivery. You will need to carefully coordinate delivery of materials with the construction schedule or you will need enough space to store the materials until they are needed.