One Ounce of water crystals. Makes 1 gallon of hydrated water gel per ounce. These are the 2-4 mm (large) water absorbing polymer crystals.

Add 1 ounce per 1 Gallon of Water
1-5 $1.10 per ounce
6-9 $1.00 per ounce
10-15 $.95 per ounce
16 + .89