I'm getting sick of hearing this same bullshit line over and over again.
The primary way fast food restaurants keep the cost of food low is by procuring huge quantities of beef from local producers, warehousing it at a centrally located facility, and bringing it in from there only as it is needed.
The burgers and fries you buy at McDonald's are the exact same frozen burgers and fries you can buy at your local supermarket.
The differences in texture and flavor are all in how the food is prepared. (Fast food tastes like crap because the burger patty is partially cooked in a warming tray until of is needed, when it is then finished off on a grill. This also gives the food the brittle, leathery texture billions of customers have grown to love.)
Creating a specialized burger patty on your own would cost more than buying generic patties that are produced in mass from a third party.