A+C if I were you, given that:

• There are orders on the closed list that will never be paid for;
• There are newcomers that want to place an order but it's closed already

...I would start a new GB instance (call it "batch 2" or whatever), where you would take new orders, and you could promote orders from list #2 to list #1 if you fail to reach the minimum 300 because of unpaid orders.