In this day and age and the loss of the family farm there is no comparison when it comes to feeding out your own meat animals.
Is it cheaper to raise your own meat birds or pork or beef when you look at it in a purely economical setting? No way. No how. Is it better to raise your own meat stock and feed it out with good clean feeds and grass? You better believe it is.
If you read up on the industry standards of what meat producers are allowed to feed the animals that are brought up to  market weight you would be sick and never want another bite of grocery store meat.
Beef and some pork are allowed to be fed the ground up wood shavings and poop from the chicken farms. They can be fed old chewing gum and wrappers - think about it - chewing gum is now mostly made with plastic and rubber not real 'gum' and the gum wrappers are foil lined.
There are several really good books that tell the truth about the commercial meat industry. Anything you can do for yourself to get your family off the commercial food grid is already a major plus - not only for you but it gets the junk and nasty chemicals out of your kids bodies. 
We (my dd and I) just finished one that caused her to change her eating habits (something I could not do over the last year because she thought I went off the deep end with home grown produce, pastured pork, meat chickens, guineas, etc over the past years)
The Real Food Revival 
I am not advocating every book or every author. There are plenty out on this subject. I find many of them to be using the subject to pass off their own liberal beliefs under the guise of scientific fact. However, there is information to be garnered and digested, even when we don't agree with every thought the authors have put down on paper.
Dollar for dollar you will not save money nor break even by raising your own meat, milk or eggs.
Edited to add - we bought/buy heritage pork = $100 per barrow, plus feed, and they get leftover bread from a bakery and any left over milk from the goats) and they are pastured on green grass.