It'll take awhile. I was half tempted to invest $13k ordering a batch.. but I did the math.
You didn't do enough math. You need to bank on other people not doing it either. Buy a whole batch and sell for cash! Yippee!
You could probably mine on them also while they are in inventory adding to your reserve!
The money isn't in mining anymore, the new money is selling shovels to suckers.