Is nouns duct cleaning worth $300? The install of our new AC have been held up because...

The install of our new AC have been held up because my wife desires to get our nouns ducts cleaned, we live in a 30+ year aged town house, but I don't see the value within paying $300 dollars for this, is it even worth it? Or a rip off resembling getting a warranty on a video game system?
Answers:    My husband is an HVAC service man and he say that that is totally pointless and a excess of money. although he does say that you should carry good filter not the cheap ones and change them regularly...
You can mostly do it yourself as long as you enjoy access to the main COLD nouns return trunk.It the one that the filter goes into lately where it connects to the furnace.Get yourself some tentative furnace filters first.Then only just turn on the fan to your furnace and move along the trunk starting from as far away as you can and moving towards the furnace hitting it near your fist as you go to stir up adjectives the dust and dirt.Go slowly and then when you catch about in the middle stop wait a few minutes Turn past its sell-by date the fan and relocate the filter.Do the same for the partner and change the filter when you are done.You wont get hold of it all but it will hold you about an 1 1/2 hr and filter are cheap