Here are some equipment suggestions:

Knee pads: 1) Black Nike Kneed pads (locally at Big 5)
                     2) Back Under Armor Knee Pads (locally at Big 5)
                     3) Black Mizuno Knee Pads (Online) (Best Choice)

Water bottle: 1) Gatorade Water bottle (locally at Big 5)​

Volleyballs: 1) Spalding Volleyball (Softer)
                     2) Molten Super Touch (Competitive)