Bro, you no need sand for your sand bag. In fact you no need a sand bag.
All you need something heavy to hold your equipment down to prevent tripping.
Use whatever from the environment. Gather some rocks or bricks or sands or soil, put them into a plastic bag will do the trick.
Normally we use low grade rice to fill our bag. If you go oversea, you can bring the empty bag and buy rice (or other grains) there, use then donate or throw after use . Save on traveling weight and not so messy.