OK, the ISI Cream Whipper is on sale at one of the big grocery stores here, for $39.99 CAD. The ad also says that the CO2 chargers are available for $7.49 (donno how many of em for that price). So I may get one; however I am wondering if you use one charger for every pint of cream? Is that how it works? Or, as DBF is saying, can you add MORE cream when it runs low, using the same charger??