I have been finding online $100 6-breaker transfer switches for the
inside (1 240v and 4 120v). The obvious drawback is that after the
well pump, fridge and heating I am limited to choosing only two rooms
to have lights and it costs a lot to have installed. My lighting is
very low watts so I don't want to be stuck in two rooms during a long
outage and I have been getting some prices around $350 to install the
box.

I would think that there should be a very simple switch out there that
interrupts the line outside before the breaker panel and transfers the
entire house over to the generator input and it would be at a
reasonable price and resonable cost to instal since it is just one
split. I can't seem to find a device like this anywhere.

In the $100 6 breaker box your getting the box and 6 breakers. In the
100 amp switches that I have been able to fine there is only one 100
amp switch and the unit costs $400. Does what I am looking for
exists? Why are these 100 amp switches I am finding cost so much for
so little?