If you want a quality trampoline than do NOT buy it from WalMart! I bought one from them three years ago for my children who were then a newborn, three years old and six years old. Within months the pad covers were starting to shred and within a year, to the day, of buying the trampoline, the whole pad was in shreds. The pad is completely gone now as well as several of the springs. The legs do not stay together and there are multiple small tears on the bouncing surface.
Since we live in the county and do not need a cage for insurance purposes, we never got one. Since all of my children are climbers, I was more nervous that they would climb to the top of the cage and fall from 10' high.
We have definitely gotten our moneys worth out of the trampoline. It is my "salvation" on days when the boys are going wild with energy and are bent on destruction. We have put it under the barn roof and they love to jump off of the roof onto the trampoline; they'll jump out of the trees onto it too. I figure, if I have a daredevil child then this is a way to get that urge satisfied.