Is house construction feasible on this scale?

I received a cost estimate. It stated, for example, -removing roof covering and old battens- x work hours / x euros. If I do that myself, the amount is eliminated = saved sum.

100,000€ is really a lot, though. Basically, you only save on labor hours by doing it yourself; material costs remain the same or even more.

I find the house expensive. Can't you first look around for other providers and compare?