There are big cardboard boxes full of ballots sitting next to the ballot kiosk at the main gate. No one will prevent you from helping yourself to as many ballots as you care to take. I visited that kiosk for more ballots several times.
The attendants at Club 4192 actually thanked me today when they saw me jamming a 3-inch high stack of punched ballots into the ballot box.
Another possibility would be to grab a big stack of ballots at the ballpark. Then, punch 'em at home and turn 'em in at WalMart.