Following items, which are needed during five days Diwali Puja, should be collected before Diwali. This list doesn't include daily Puja items but it lists only those items which are needed especially for Diwali Puja.
New Murti (Idols) of Lord Ganesha and Goddess Lakshmi
Bahi-Khata (Account Books)
One red silk cloth for Goddess Lakshmi, One yellow cloth and Inkpot with pen
One red cloth for God's Aasan (seating)
Wooden stool for keeping Murti(s)
Five big earthen Deepak (lamp)
Small earthen Deepak (at least 25)
One fresh earthen Kalash (pitcher)
Flowers and at least three garlands made of fresh flowers
Bilva-leaves and Tulsi-leaves
Naivedhya e.g. sweets, fruits, sugarcane, Lava (parched rice)
Sweet Paan (at least 3)
One pen made of pomegranate or Bilva branch
Duba (दूब) - Durva grass
Pancha Pallav(पञ्च पल्लव) - twigs of following five trees
Sarvoshadhi (सर्वौषधि) – ten following herbs
Sapt-Mritika (सप्त-मृत्तिका)- mud collected from 7 places
If some of the items are not available then Akshata can be used in place of missing item as a remedy.