Amazon offers the Ziploc Slider Gallon Storage Bag 32-Count 3-Pack (96 total) for $9 with free shipping via the steps below. That's the lowest price we could find by $2. They feature an expandable bottom to fill while standing. To get this deal:

1. View the Ziploc Slider Gallon Storage Bag 32-Count 3-Pack for $12
2. clip the 20% off coupon on the product page
3. order via Subscribe & Save for a final price of $9

Note: Be sure to cancel your subscription after receiving your item to avoid being billed for subsequent shipments.