The closest thing to a home cardiac monitor would be the at home defibrillator which is the machine used to shock the heart when it is in a death defying rhythm.
It's a good idea for some people who fall into the target risk group to have access to defibrillators, but this is not the type of thing that every family needs to stock like Band-Aids in a medicine cabinet. It comes down to whether you think the risk is high enough and it's worth the money to keep around. If you are at risk, you should be under treatment.
It is not a machine used to check your heart rhythm but a piece of emergency equipment.