In link below you can find complete bill of materials for electronic modules. Bill of materials of the complete assembly can be found in attached files.

Project cost (approximation):

• Electronic components ~35$. 
• 3D print of enclosure ~15$. 
• Li-Po battery ~6$. 
• PCBs  ~20$. 
• Strap holders and straps  ~10$. 
• Magnets  ~5$. 
• Screen protection acrylic ~2$.