I used to buy 5*200 visa cards in OD and liquidate by AME targets. The cost is:
5*6.95+3=37.75
The points I got are: 206.95*5*5=5174
37.75/5174=0.0073$/mile
If you buy vanilla in drug store, you paid 3.95 for 504 points if there is no bonus.
3.95/504=0.0078$/mile
almost equal