Central Air Unit

It’s time to upgrade. 1150 sq ft in CT, thinking 2.5 ton, something greater than 16 seer gets me a $600 tax credit. Any recommendations on units? I had an insane shoot from the hip estimate to replace from a tech last year, $18K?! Other than the unit, refrigerant, and labor, what else needs to be done? What should a reasonable quote be? Thanks everyone! Learning here, any advice is appreciated.