The one I always recommend is the Estes Flash launch kit.
It's widely available, builds quickly, is sturdy, doesn't fly too high on A8-3s which makes it perfect for park launches, and lastly, because I have two of them that have never disappointed me.
From the economics side of things, you get the rocket, the launchpad, and the launch controller all for under $30 at the local hobby shop. Paid only $17 a piece for my two birds a Wally World but they no longer carry Estes rocketry products.
Kit (AKA Cranky Kong)
Total Total Impulse as BAR: 7,753.69 Ns (Equivalent to a 51% M motor.)
On any number of government watch lists...