The most obvious cost of paintball is the cost of the paintballs you shoot.
Cheap paint begins at about $30 for a case of 2000 rounds or about $10 for a box of 500. Professional grade tournament paint can cost as much as $80 for a case of 2000. Keep in mind that if you play at a professional field you may be required to purchase field paint which can cost significantly more than the paint available at your local Wal-Mart. The faster your gun shoots, the more you will tend to spend on paint.