Actually the max price you can sell an item at re-tail is 999,999 bells, so you'll have to buy an item 20 times. The people I traded with previously bought the item, then they drop it outside for me to put up again, and we just cycle and repeat until the goal is reached. 20 trips is equal to 19,999,980 bells, so let me know if you want me to re-list the item a 21st time for 20 bells, or if you'd rather just drop 100.