Is $1,750 to install R-38 attic insulation a fair price?

My brand new a/c is struggling to keep my house at the set temperature, so I’m really hoping this will help. I had an energy auditor come out today and he showed me all the places inside the house where there is air leakage and showed me where I need to caulk/seal. He said the main issue was the insulation and ventilation though. I was told by a few companies I called that the blown-in insulation will seal the attic. I asked a few companies about air sealing the attic and they said the insulation would seal it. Is that true?