I have seen people on all income levels on Location x 3, but there is no point on somebdy being on the programme if there is nothing they can afford in the area they want to live.
I like it because the people on it are actively house hunting and do actually offer for and buy property. They also have people at all levels in the housing market.
Some people do have significant equity behnd them but that can come from anywhere, from equity from previous homes, to inheritance, to a lottery win or a business sale.
I knew someone who moved to a beautiful large house, after her parents died in a road accident, whether the new neighbours knew that was the reason the young couple next door could afford their expensive new house, I do not know.