How much and where would you find a whole house vacuum system?

Answer 1

My son had a whole house vacuum system installed when he built his newest home.
Their place is (3) floors, about 1500 sq. ft./floor.
The collector is located in the garage.
They used and liked the system untill one of the family members came down with some allergies and then they opted to switch to a more powerful standard portable vacuum unit, which is what they use now.

You can go on the internet and search under "Central Vacuum Cleaning Systems" to find suppliers of those systems, and write to them or call them to get price quotations for their equipment installed or do it yourself.