Does paying labor count? I've had this house 45 years and ducts have never been cleaned!

The ducts were put in best I can tell in 1968, the new addition 1995. I did research and found a great business, man & his wife working together. They really had lots of equipment, ion generators & vacs running while they used power brush & UV light.
When through hours later the ducts looked brand new inside.
The guy wanted to reduce my bill because I took all grills to garage, washed & replaced foam gasket.
The old house smells brand new & no dust when furnaces run!

$700 to me days work was very fair.