We have just started ttc, and so I decided to bring out my old BBT that I used to use just for basic charting.  Sadly the battery was dead :(, so I stopped into my local Shopper Drug Mart today to grab a new battery.  After digging through the shelf I found the correct one and made sure I check the matching sticker for the price.  When I got to the cash it scanned for 4.99 instead of 2.79.  I played the scanning code of practice card and got me a free battery!  Hopefully the rest of the day stays on the same foot!