Sorry no comments on building your own except that they may keep your pup inside the fence, but other animals can get in and start trouble for your dog. Not sure of the area you live or if you have wildlife your pup may want to chase out of the fence.
We used to just buy from the co-op and they were pretty cheap there , had to put them together but it all came as a set just added more line depending how big we wanted the run. Used it for our horses while the barn was being built .
There are two kinds, the underground fence you cannot make at home, that is a collar and wire device. Then you have a hot wire that you can do yourself.
My question is what are you trying to prevent them from doing? both have limitations on how you use them.
We have a private fence up but we are having trouble with one of the neighbors. They "own" that side of the fence and are trying to start a fight bout our dogs messing it up. So we were thinking put up an electric fence to make the dogs stay off it.