Simple living is having only what is necessary and fewer items is called minimalism.
Life in the past and rejecting modernity is known as old-fashioned living. Living modestly and trying to save as much money as you can is known as frugal living.
Making what you require and purchasing as little as possible is self-sufficiency.
These are all reasonably close, but none of them are perfect. Because contemporary, expensive, or dependent is not the opposite of simple. Simple is the polar opposite of complicated.