If you think you will eventually be moving up to more complex forms of low-power rocketry, or even to mid-power, you may want to skip the Estes controllers and move straight to one of these other recommendations.
Don't get me wrong, for low-power blackpowder motors and Estes-style igniters, the basic Estes battery-powered launch controller works fine. (The 'big brother' for E motors also works fine.) They will handle many years of basic (single motor) low-power operations. When the batteries are fresh these controllers will usually handle a two or three motor cluster.
However-
If you plan to have a busy launch day you should bring one or two changes of batteries for those Estes controllers. If you plan to launch a lot of clusters, or a large cluster with gobs of motors, you will want an electric power source with a lot more amps. If you plan to launch much mid-power stuff, you will definitely want the longer lead wires (for safe set-back distance, as well as getting a better view) which kinda also pushes you toward a better electric power supply (better than a handful of AA batteries).
To improve the levels of electric power at the launch pad you may also want to have a relay system; this uses lower power levels through the lead wires and uses an electrical relay at the launcher itself to switch the electric power for actual ignition, and usually provides better results on clusters (and pretty much everything else too). The Estes launch controllers do not offer this feature.
There are hardware products out there that can easily double as electric power supplies. If you have a riding mower you could borrow the 12V battery from it. If you have one of those portable power supplies for jump-starting cars, it includes a 12V battery with plenty of power. A lot of guys have converted gel cells and electric tool batteries from other uses.
I hope some part of that answers your qstn---