IMO, the "off the grid" term is too flexible. At one end it's a 100% sustainable living, which is extremely overwhelming if you are limited to your ranch, if there are no people around (to help and trade), and if your family is not big enough to harvest/produce all of the necessities efficiently.
On the other hand you can find a lot of help in the right technology, and in fact you are never really isolated from other people (unless you are in TEOTWAWKI situation). Simple example - there are hordes of homeless people living completely "off the grid" in a much more real sense than Les' family in that show.
What Les is doing there is just demonstration of the ways to cut some expenses which seems unavoidable to the common knowledge. He is going shopping to the mall for supplies anyway.
I believe there is no other job possible for living off the grid people, except the full time job of surviving off the grid

Otherwise it will be hard to survive or that's not an off the grid living. Money belongs to the grid.