Why do you want to acquire, move and add this house to your existing house? There must be some motivation to do this.

In all likelihood, a custom-designed and built addition to your house will be better integrated aesthetically from the exterior and will integrate better with your interior functions and rooms, since it will be designed from the outset to do so.

An existing house will have a lot of "blending" to do in order to not look like a house from down the road that was moved and nailed to your house, plus having interior uses blend seamlessly.

What motivates you to move and add this house?

it really depends upon how wide and how tall the place is.
google housemovers to get some prices on the project.