Your experiences, while valid for your area, are rather different than mine. I paid cash for the total engine package in-a-crate, and then negotiated a install contract for a near-fixed amount with a good ship wright.... and then did a lot of the 'grunt' work myself. We changed the engine out at our slip.
There is at least one large yard in my area, tho, that might do just about what you are describing. I try to avoid their "services."
The total labor bill did grow some, but that was my choice -- updating electrical and piping stuff that can be best done while the engine compartment is empty.
I did a little glass work, and installed new sound deadening, and then reformatted the fuel supply and filter system.
IF...... I had to pay a commercial yard for the whole thing, it would have probably added another 4 or 5K to the project.
Good thing your sailing area is a paradise compared to our river venue! Everything's a compromise, as the saying goes.