if you're buying coke in america, you should get the 12 packs at grocery stores instead. it's anywhere between $5.99 to $8.99, which is less than a dollar per can
most people are getting cans like that in a pinch tho, if you want a lot of cola, regular 2 liter plastic bottles (or even better, 6-packs of 1.5/2l) are a much better deal
Wow good point! Water IS cheaper than coke! And healthier too I'm sure! It's a damn shame we're talking about coke and not water, or else I'm sure someone would give you a prize for your thoughtful and original comment.
Yes, it probably won't be completely flat after half a liter but the fizzyness will be noticeably weaker and will only get worse the more you drink, especially if you don't get to it soon. Two liters are ok if you're sharing them with multiple people who will finish it right away or the next day but they suck for one person unless you drink a ridiculous amount of soda.
Not on sale? Where I am, I only see the $7 price when it's on sale and you have to buy 3. So it's 2 for $10 and get one free. Without that the normal price is about $10. The best sales that come around during big holidays only are buy 2 get 2 free, which brings it down to $5.